# Would oceans filled with long-lived, omnivore, intelligent Krakens make sea travel impossible?

Let's say the oceans' apex predator on a planet similar to Earth is a species of Kraken (octopus, just big huge ones) that live 200 years in average (so they have plenty of time to develop their cognitive skills), and have basically the same capacity to develop intelligence as Earth's octopus (that don't do as much they should do just because their lifespans are too short, according to research as they have more neural building cells and cell types than we have).

They are very intelligent and evil, not simply clever, but able to understand patterns and develop plans to ambush and catch their prey, besides many other things (building, communicating, using tools, so on). The live in the oceans because they are a underwater species and because a large creature usually will choose the ocean to live because "there is plenty of fish in the sea"...

So, what I need is for them to make it impossible for the human societies that live in that planet to travel by sea. As that planet is bigger than Earth (gravity is a little stronger) and atmosphere is thicker (2.8 Earth atmosphere but with plenty of Helium - around 28% of atmosphere), airship travelling will be common, but I need to make it impossible to travel by sea so the only option remaining for long haul travel are the airships.

• Not related to your question, but if your atmosphere is highly helium, you're going to have a hard time using it to achieve buoyancy for air travel. You want helium inside the airship and a heavier gas outside. May 11 at 5:24
• @gregsdennis neh, while 28% helium in the air will reduce the buoyant effect of the pure gas a bit, at worst it only reduces it to 72%. the 2.8 bar pressure will more than make up for it. And with atmospheric helium that common, it will be easy to concentrate. (about as easy as it is for us to make liquid oxygen from air). Or easier, you might get away with using large silos of still air, and natural settling, to extract ever-higher concentrations of He from the top. May 11 at 7:43
• @Jontia The removal of oceans has much larger consequences, such as the extinction of most life on the planet. May 11 at 12:24
• How intelligent do you mean? Dog intelligent? Or would you allow for them to reach human intelligence levels?
– Len
May 11 at 17:55
• Not sure why you feel the need to specify your atmospheric content, but the helium is irrelevant for any practical consideration as it doesn't just mix together with heavier elements. Helium is sourced by tapping trapped air pockets underground (byproduct of natural gas wells), because it rises to the edge of space (or escaping entirely) instead of thoroughly mixing with gases such as Nitrogen and Oxygen. For Helium to be such high concentrations in the lower atmosphere it would need to be constantly bubbling up everywhere. May 12 at 15:42

Octopi play.

source

The ocean can be terrifying. More terrifying is being played with by an intelligent predator. It grabs a person then leaves. It hits the boat and then leaves. It throws a huge live eel on board. It scratches at the bottom of the boat. It pulls the boat along and then stops. It puts the person it grabbed back onto the boat and he is not dead.

This does not happen all the time. Sometimes the boat just disappears. But sometimes there are survivors who tell stories of how their boat was turned over and pulled underwater, and they lived in the bubble as the kraken took them one by one. These stories are so terrifying that no-one wants to go to sea.

• Orcas are known to sling manta rays and other animals in the air for no other reason than for kicks. I honestly don't doubt ,assuming they'd also be strong enough, there'd be stories of sailors who suddenly saw something big swim below their small ship and in the next moment found themselves being forcibly shown how the view of the open ocean 30 meters above sea level looks like May 11 at 1:59
• Don't forget that dolphins (another intelligent seadweller) will slowly murder other species for their own amusement. Not that much of a stretch to see a Kraken doing it. May 11 at 10:14
• New meme format? May 11 at 20:50
• @JoeBloggs [citation needed] May 12 at 17:48
• @LarsH he's not lying, dolphins can be perverted jerks when they want to. May 12 at 18:37

I am not sure that those kraken would consider human ships interesting prey. After all most of the ship is inedible (wood) and hunting those little, pesky critters hugging to the "huge log" is time consuming and may be painful. Such super predators may, on the other hand, decimate marine life in similar way to how humans did it. Then they may start to search for food on the coasts.

The problem is sea travel is extremely efficient in bulk transports, especially early in history. And early on, the seas were super dangerous even without the hunting octopi so if they are rare enough to not destroy marine life, they may become just an additional, acceptable risk. After all from 270 men and 5 ships Magellan took for his first circumnavigation, only 18 on on a single ship barely returned home.

• Assuming of course that the kraken only hunts for nutrition and not because it’s territorial, naturally aggressive or (given how smart it will probably be) just plain sadistic. May 10 at 21:27
• Sure, if they consider a ship to be enemy situation looks differently. May 10 at 21:36
• "inedible wood" plates are inedible but humans love them for the tasty morsels that they serve... they are smart and appreciate the fancy treats... May 11 at 5:33
• If the op data is correct and this kind of octopus can live that long, it will become very smart. With intelligence comes curiosity. I would find very interesting the great thing that moves on the surface full of unknown things and creatures that do not breathe in water. May 12 at 7:13
• I wouldn't be so sure, since octopuses are also naturally curious, and their main method of exploration is through their tentacles. I could easily see a giant octopus investigating a ship, getting hurt by the sailors and proceeding to see the ship as a threat and sink every ship it finds just to be safe. And if you think that's absurd, let me tell you about the giant pacific octopuses that would murder the sharks in its tank for the grievous crime of...swimming too close to it. May 12 at 21:45

The human skull is an aphrodisiac

By a part of the kraken society, it is believed that the skull of a human when eaten is a powerful aphrodisiac. Illegal trade in human skulls is very profitable, so some less ethical kraken hunt humans for their skulls, even to the point of extinction where they can't be found on the surface of the ocean anymore.

This is a fictional scenario and of course could never happen in any real-world setting.

• Not sure the trade by Kracken needs to be illegal or even considered unethical. If Kracken society does not consider humans as 'real people' then why not collect and trade a powerful drug? May 11 at 9:32
• That's a great idea, as it solves the problem of why the Kraken would bother attacking ships when fish are far more common. OTOH, they would probably have started by attacking fishing boats, as those humans would be stealing their food. I like how this is the solution to your observation that Kraken hunting humans is like humans hunting lions or elephants. May 11 at 14:34

I'll vote yes... but with a caveat

Humanity has proven itself capable of exterminating everything else on the planet save itself. And frankly, it's proven itself more than capable of exterminating itself (from small genocidal actions to M.A.D.-capable nuclear arsenals) given only that the better angels of our nature have (so far!) held sway.

Which means your kraken have a problem. If they're restricted to the sea, then humanity (which is NOT restricted to the land) will eventually figure out ways to destroy them. If only the wasteful practice of dropping continuous depth charges around ocean-going vessels (more likely flotillas for the sake of efficiency) is used. The only reason the bad guys could rob trains is due to the restriction of resources needed to keep the trains fully defended. The same is true of ocean-going vessels today. Place twenty armed soldiers with firepower on each superfreighter and Somali piracy would become a thing of the past.

But that's important...

The biggest thing going for you is economics. Let's assume that your world boasts 67% water like Earth does. That's a heckuvalotta ocean. Our land masses support short of 8 billion. Now, to be fair, we use the ocean to feed our people... but that same ocean is also feeding all the oceanic life. What does this mean? millions-to-billions of kraken. It may be too costly to regularly ship by ocean.

But you asked for making it impossible

And that's the other side of the coin. Given enough resources, humanity has always come out on top. If we assume your kraken are equally intelligent, they still have the problem of being restricted to the water. They can't take the battle to the humans on dry land. That's a serious disadvantage — but disadvantages are important, too.

TL;DR

• Humanity, as always, can traverse both land and ocean — and use the resources of either. But they are weak on the ocean, subject just to storms (much less intelligent attack!). This means they can overcome any kraken attack — but at a boatload of cost. That means basic trade is out. Most military campaigns between continents (by sea) are out. Once airships become economically cheaper, they'd take over nearly all if not all intercontinental transport.

• Your krakens can't move on land, but they have numbers. Humans on your world can't draw from multiple continents to defend themselves, but the kraken can quite literally draw from the entire planet's oceans. That's as much part of why it's so blooming expensive for humanity to defend themselves — and why submarines are absolutely out. I believe it's reasonable to conclude that if it's economically impractical-to-impossible to successfully defend against a single-hemisphere attack on the surface, it's well into the impossible zone to defend against double-hemisphere attack underwater.

• Finally, to support the workings, trade tends to take the path of least resistance (both physically and economically). This justifies your airships.

In conclusion, it's economically impossible, but not technologically or militarily impossible (which would be unbelievable).

And heaven help the humans if the krakens ever learn to breath in fresh water. If they have a Nile or a Mississippi, an Amazon or a Volga... then even the continents are divided. Yuck!

• "submarines are out" but the first country to communicate and create a treaty will get a sup'd up version of trained dolphins... en.wikipedia.org/wiki/Military_marine_mammal May 11 at 5:37
• @WernerCD ...and then they wipe out the rest of humanity with the krakens help, and as they're celebrating their final victory in the submarines the kraken pull them all to such a low level the pressure collapses them. Krakens win that one, now lording over the small remaining human population on land, requiring food sacrifices to control our population and grow their own further May 11 at 17:25

If the kraken are similar to Earth octopuses, and the humans are at a similar (or higher) level of technology to 2021 Earth humans, it won't work. The humans would have developed boating on inland lakes and rivers, and eventually come up with the hydrofoil or the speedboat, to foil (sorry) the slow kraken.

Perhaps the kraken could build some large acoustic mirrors underwater to detect the speedboats from far away (sound travels even faster underwater than in air). But what materials would they use to construct these? They have no trees for wood. They cannot smelt metals underwater to create tools they could use to mine rocks to build large structures. Perhaps they could use their beaks to hack away at rocks?

Without these resources, how would they have developed any technology worth mentioning?

And what motivates the kraken in their hunt for humans? As Archelaos pointed out, there is not much meat on humans, whales would make a far better meal. If they've wiped out all other oceanic species, it's more likely that they'd turn on each other for kraken-sized snacks, leading to a rapid octo-depopulation.

Is it perhaps the wood and metal from the human ships that they're after? If so, then it would be more beneficial for them to let 9 out of 10 ships pass and thus keep the ocean trade economical. Rather than completely preventing maritime travel.

The only way I can see this working is if some human faction has found a way to enslave the kraken in order to control the oceans. Perhaps humans who live on islands, away from the continents, and felt threatened by the large continental navies? These humans would have the technology to detect ships from a distance and send out their tentacled minions to intercept.

As a side note, what do you mean by calling the kraken 'evil'? Are they self-interested? Have they wiped out most other species in their ecosystem? Well that would be no different to the Yours Truly apex predator.

• There is also not much meat on lions, yet they are hunted. There is even an enormous amount of meat on an elephant but they are not hunted for the meat. May 11 at 9:16
• @D.J.Klomp ah! maybe Krakens hunt animals not for the tiny amount of angry meat, but for the large amount of useful buoyant construction material they sit on... and sail cloth for plankton farms. May 11 at 16:27

# No

Except for tool usage, your krakens have all the same psychopathy and viciousness as orcas. They are intelligent, social, learn patterns and develop new hunting skills over time on their own. They are also cruel as cats in that they will **** up other animals without necessarily killing or eating them. And if they so wished, they could probably team up to damage Age of Sail craft - they could break the rudder or damage the keel, for example.

And yet they let us be, simply because there is nothing to gain by trying to take on sailors. In fact, despite all their physical might and intelligence, orcas were historically hunted by humans. They still are to this day (looking at you, Norway and Japan).

If they are truly intelligent, cooperation can bear more fruit to them than hostility can. They would opt for that even if they are cruel and evil in nature. If your krakens learn to communicate with humans, they might make sailing difficult by charging a toll on the safest routes (and that toll might not be fair to humans).

• Orcas are not currently hunted by Norway or Japan. This is both due to international pressure and the fact that the are pretty difficult to catch. There is a really low demand for whale products (especially in Norway) so they mainly target easy to catch species like minke whales. May 11 at 17:59

Depending on size and level on intelligence, such a creature could very well make not only travel by sea suicidal, but also coastal living.

There are stories of "mini-kraken" using ink jets to turn off lights and if legends are to be believed, an octopus in captivity would hunt in other tanks at night returning to it's own tank full of fish by day break.

https://www.slickrock.com/2013/08/octopus-facts/

If the the stories of nighttime raids by hungry octopi are based on some sort of kernel of truth and if they grew to "only" 500kg (size of a horse) then I would not think anyone even behind doors would be truly safe either at sea or on the coast.

I honestly don't think you need to make it impossible.

For humans, sea travel was long the quickest and most reliable method of transport. However, even under those conditions, traveling the open ocean out of sight of land is a feat only literate socities ever developed. Its a technology.

All it would really take to "fix" that would be to make it less reliable than ground transport. People under those circumstances might still hazard short coastal trips (because its still quicker), but ship travel would never become popular enough for anyone to have either the motive or the opportunity to develop open ocean navigation techniques or open ocean safe ships.

So the Krakens wouldn't have to get every ship (which is good, because even WWII era navies couldn't promise that. The ocean is freaking big). They'd just have to get more of them than predatory humans of that era get caravans.

• FWIW, there are in fact Giant cephalpods living in Earth's oceans today. However, they don't live more than about a decade, don't appear to be significantly more clever than their economy-sized brethren, and seem to spend most of their time trying to avoid being eaten by sperm whales. May 12 at 18:48

## No

Its really just a question of dispersal. If your krakens are large enough to threaten ships they would need a large amount of food just like whales (or the giant octupi that live on them) do.

The limited numbers means that they can't possibly cover enough of the sea to actually be enough of an issue.

This would mean that unless the sea is so extraordinarily rich in life so that its chock full of krakens with nothing better to do then hunt ships outs of pure malice the chance of actually encountering one would be very low. If it is that rich in life the incentive for going to sea and hunting krakens would be immense.

Some better alternatives:

• Extremely unpredictable and stormy seas.
• Extremely calm seas. Without trade winds you won't have intercontintental travel until you can provide power for the entire journey.
• Super hull eating barnacles.
• Poisonous algae blooms.
• Swarming creatures (like mini kraken) that attack and overwhelm sailors.

### They don't hunt the most dangerous game

Attacking humans is low reward for the effort required. Fishing vessels loaded with a haul, well, that's different. Let those poor defenseless schmucks do the hard work of gathering up a nice lunch buffet, then waltz in and take it yourself. And if they're intelligent, they'll be able to figure out the difference between fishing boats and normal boats. (Which is another way of saying there won't be any fishing boats, if these kraken are nasty enough.)

## They attack for some other reason

The other answers have covered some other reasons already. Here's a few I didn't see.

### Disgust

They see people as vermin. They react to people being in their territory the same way most people react to a cockroach or rat infestation in their home: terminate with extreme prejudice. The whole ocean is their territory, and they're fastidiously obsessed with keeping it 'clean and neat'.

### Anger

Long ago, the kraken mostly left people alone. Then people started hunting them (the way we often do). Turns out krakens aren't just intelligent, they have a society and long memories. In our world, when (say) a bear turns into a man-eater, we go to great lengths to hunt it down and kill it. Add on top of that a mean-spirited and evil disposition in general, and it's not hard to picture kraken killing any human they can find out even a long time afterward.

They think in the long term

These octopi know that there is a sentient race that inhabits the dry lands where no octopus ever could set foot tentacle.

Octopi also know about these creatures that

They are very intelligent and evil, not simply clever, but able to understand patterns and develop plans to ambush and catch their prey, besides many other things (building, communicating, using tools, so on). The live in the oceans dry lands because they are a underwater air-breathing species.

Now, there is a problem for the octopi: these creatures can also ride the surface of the waters and threaten the octopus species in its own lands, while octopi cannot do the same.

Since nobody knows what evil plans these air-breathing creatures could develop in their rear lines if left undisturbed, octopi feel they have no other choice than striking first every time they can, in order to hinder human seafaring expertise and keep them the farthest possible from their breeding seas.

Basically, their purpose is exactly to avoid humans to learn and master sailing abilities (destroying the first ships and making impossible to travel by sea will prevent accumulation of experience and technology in advanced sailing), and gain time while trying to developing technologies that could allow them to attack the dry lands and human dwellings.

If you are looking for impossible, the I don't think intelligent kraken are going to do it. We actually have a good analogy for this situation already in human history. Improvements in submarine technology made trans-atlantic shipping extremely hazardous during WW2. A German U-Boat could be lurking anywhere and they were capable of destroying a ship before the target even knew what was happening. Even with that threat, shipping and trade continued. It lead to the development of tools like sonar and depth charges and to new tactics like protective convoys. The economics of shipping large quantities of heavy goods means that you are going to need a lot more than a few lost ships to make people abandon the seas.

The real question to ask is, why is excluding the possibility of sea travel important to your story? If you just want to restrict passenger options, the existence of air travel already does that. As soon as air travel becomes a viable option, it will make sea-going passenger vessels obsolete. If cargo is what you care about, making the seas impassible won't suddenly make air-transport of cargo viable. Some finished goods might get shipped by air, but you are not going to be bulk shipping iron ore or grain that way. That stuff will either travel over land or end up too expensive to ship at all.

by making air travel less difficult it would make sea travel more difficult.

1. provide the humans with an easy, safe and fast way to travel by air, and they'll choose air instead of sea.

2. You mentioned the planet has helium in the atmosphere; helium may make it more difficult for air travel, because helium is lighter than oxygen, and therefore it'll be more difficult to float in helium. Consider making the air of a more dense inert gas, like Argon or Xenon, so the humans and any aircraft they build can more easily become buoyant.

3. Consider reducing the planet's gravity so that it's easier to fly. Perhaps the core of the planet could be made of a less dense Copper instead of the more dense Iron in as in earth.

4. As for making the oceans 'virtually' impossible to travel, perhaps you could introduce deadly persistent storms, or the ocean could be made of a poisonous miasma, or perhaps the oceans are filled with rocks that hide just underneath the surface and easily scrape ships that pass by unaware

• High gravity makes flight easier for airships, not harder. The higher air pressure means lifting gasses are even more effective. May 12 at 16:16
• The reason high gravity increases air pressure is because it increases air density. but reducing gravity doesn't necessarily equate to reducing the air pressure. The density of the heavier Xenon gas should increase the air pressure. Secondly, not all airships rely on air density for lift. Consider a helium balloon, which does not "generate lift". It would be much easier for the helium balloon to gain bouyancy in an atmosphere of Oxygen, than it would to gain altitude in an atmosphere filled with Helium. May 12 at 16:35
• By definition airships rely upon lighter-than-air gases for lift - that is what makes them airships. That you have to assume the requirement of a complete change of atmospheric composition along with any changes in gravity reveals your flawed argument - given the same gases, higher gravity makes Helium-filled airships more efficient. There is no requirement for different gravities to have different atmospheric compositions as they are independent factors. Furthermore your point that Helium is not a lifting gas in a Helium environment is both tautological and entirely irrelevant. May 13 at 19:30
• Earth's Helium is 0.000524% of the atmosphere. If it were increased to 28% as the Original Poster suggests. Then all helium balloons or helium-filled airships would have more difficulty floating. So I'm only suggesting the OP to reduce the amount of Helium in the air to therefore make it more easy for helium-based balloons and airships to lift into the sky and to be able to carry more weight. So let' May 14 at 16:32
• See this post for calculations involving reduced gravity but still being easier to fly: worldbuilding.stackexchange.com/questions/18665/…. May 14 at 16:46

There are stories about gigantic squid or octopuses attacking and even sinking ships.

There is one story which seems more plausible than others and might possibly be true.

https://www.jstor.org/stable/23731245?seq=1[1]

https://www.amyeyrie.com/giant-squid-the-kraken-revealed/[2]

And it is a fact that even today boats and ships sometimes are damaged and even sunk by encounters with sea life.

For example, in recent years at least two fishing boats have capsided when they tried to haul up nets with too heavy loads of sea life. In one case the fish in the net included a ten ton basking shark who may have damaged the fishin boat thrashing around.

And small woodern sail boats - which are as large as many of the small wooden ships which used to sail across oceans - have been damaged or sunk by accidential or deliberate collisons with sea creatures such as orcas and pilot whales.

So if small whales can sink small wooden boats or ships, what can larger whales sink? Larger wooden sea going ships.

It is hard to find trustworthy information about ships sunk by whales on the internet. For examples, various mentions of the great white whale Mocha Dick give different numbers of ships they claim were sunk by him, from zero to about two dozen.

But I am pretty sure that at least ten sea going sips were sunk by whales in the last few centuries, in either accidential collisions or deliberate attacks. One source claims that one of those ships was sunk by lashes from the whale's tail, and another ship is alleged to have been sunk by a whale jumping out of the sea and landing on the deck.

And there are other alleged cases of ships sunk by whales in that period which might be accurate.

But hundreds or thousands of ships sank every year from other causes, and that didn't scare people from going to sea in those centuries.

So I don't know what would hve happened if the great whales adopted a policy of attacking and sinking very ship they encountered, which would have been hundreds every year. Humans should be greatful that they didn't.

Long distance explorations would probably be next to impossible, if the Kraken consider human vessels good prey, or interesting catches in themselves. Such large beings are unlikely to be so numerous that short voyages in shallow waters would often encounter one.

There are a few notes:

You specified that they are intelligent: Intelligent beings can be reasoned and bargained with. It is very likely that humans would have access to something from land that the Kraken would value very much, and so someone might first buy them off, and eventually even buy the protection of a few Kraken against others. There needs to be a mechanism for this to not work. It might be that the creatures are less inherently social, and in the end not very trustworthy at all. Think of how little control you have over cats despite having total control over their food.

Cavemen hunted massive animals to extinction in prehistoric days. You can accomplish a lot when you put a bunch of tiny humans with smart brains together, and a collective goal in mind.

All the humans would do is modify their ships to go kraken hunting, because humans like to attack what they fear and prove their mettle. So, they'd have kraken hunting ceremonies, possibly as a right-of-passage for manhood. But, the kraken will also have resources the humans can use...

• the meat can be sold
• the body parts (eg: the beak) sold as trophy to wealthy people
• the ink sold to writers / alchemists
• various body parts and fluids sold to alchemists, collectors, etc

The ships the humans made would evolve into something that would give a kraken a run for it's money, like massively over-engineered timbers and structure that could prevent a kraken from breaking the ship apart. Surround the outsides with spikes and things that hurt the kraken if it tries to wrap a tentacle around the ship. Dump massive loads of some kind of fluid into the water that the kraken doesn't like if the kraken gets the upper-hand. Cannons with chains would get fired that would act like saws flying through the air to shear the kraken's flesh and limbs.

Humans would find a way to fight and benefit from the kraken..possibly hunting them to extinction if the kraken didn't learn to avoid the ships.

Think of it this way...

In the Dishonored video game series, they reinvented whales into these nasty, sharp-toothed prehistoric buggers that would tear ships apart.

The ships evolved into metal-encased death machines that went out hunting the whales, b/c a) the whales were dangerous, b) the whales had valuable resources.

The same would happen on your world as the humans feel it's their imminent domain to conquer all.

The thing holding them back would be resources.

One reason the Native Americans in the United States lingered in progress compared to other people in other countries is because they lacked easily-accessible resources, like metals. While the Chinese were inventing gunpowder and fireworks, the Native Americans were still living in tee-pees and shooting bows-n-arrows.

So, the resources the people on-land had available to them, and the technology to harvest, process, refine, manufacture.. that would be the limiting factor.

If your humans are still running around with canoes and stone weapons.. yeah, stay out of the water.

But, if the humans advanced to metal-working, steel manufacturing, large timber working, etc... those krakens' days are numbered.

It depends on how readily available the resources are, and how well-equipped the humans can get to them... and then how smart they are in refining and using them.

• One of the main problems with the argument that we hunted massive animals to extinction as cavemen is that these animals were usually around mammoth size, not colossal sea monster size. The second problem is that certain strategies we used a lot to hunt these large land animals involved traps that made use of the animal's weight, like leading them off cliffs and digging ditches, both of which won't work as well in a giant marine octopus that can destroy boats like an Orca can destroy seals. You might need to first reach a higher tech level before you can scratch those marine monsters. May 12 at 18:29
• Also be careful about the resource argument. Natives in Brazil had so many natural resources that there was simply little to no need to develop new technologies like wide scale metallurgy. Culture is also a very important factor May 12 at 18:33
• @ProjectApex third problem these hunting strategies rely on the general stupidity of the animal being hunted. harry and panic tactics don't work well on an intelligent creature
– John
May 14 at 0:53

## Air Ships Cost to Much

NOTE: For best comparisons, I will show all prices below adjusted to today's currency using https://www.usinflationcalculator.com/ since everything below was made over the course of about 8 years.

There are a lot of answers addressing why shipping would not stop, but let's instead look at the problem from the other end of the spectrum. Could an airship actually replace ships if they had to?

The short answer is not really. Using the LZ 129 Hindenburg as an example, it costed about ~\$55.6 million in today's currency for a useful lift capacity of 102 metric tons. That equates to a total cost of ~\$545,000 per metric ton of capacity. Now at about the same time, using the same level of technology, the type C2 cargo ship costed ~$50.1 million for a very similar cost to the Hindenburg; however, where carry capacity was concerned, there is no comparison. With a useful capacity of ~4938 metric tons, the C2 cargo ship only costed ~\$10,145 per metric ton of capacity.

At this price disparity, airships would be over 50 times as expensive to use as freight ships. Considering the cost, there is no way a practical society would phase out naval shipping.

At most you would see airships become the preferred method of travel for rich businessman and political leaders who wish to trade the higher cost for the better chance of survival. To put this is perspective, a trans-atlantic passenger trip on the Hindenburg was priced at ~\$8,345 in today's currency; so, it could never be the preferred method of travel for your average joe. ## ... but arming merchant convoys to the teeth does not In WWII, allied freighters faced a similar threat in the form of German u-boats. These u-boats sank 2,825 merchant ships over the course of just a few years, yet this did not dissuade people from using ships. Instead, we just saw them get a lot better protected. By the end of the war, your standard heavy convoy consisted of a carrier worth about \$1,038 million, 6 escort destroyers worth about \$89 million a piece, and ~50 freighters comparable to the C2 for a total cost of ~\$4,077 million resulting in a cost of \\$16,513 per metric ton of capacity in today's currency. So instead of spending 50 times as much on freight, by militarizing our shipping, we only had to spend about 50% more.

Make a sub-species of Kraken live in the shallow waters near the shore. If humanity is scared to go near the ocean, they'll never try to build boats, and if they do they'll be destroyed before they can get in the water.

Yes ... with a couple of assumptions

Firstly these Kraken's are not just intelligent - they are social enough to want to form societies.

Secondly these societies develop at roughly the same pace as those of the land dwelling humans.

Consequences Populations of Kraken "towns" spread across the seas, halting all human crossing of anything but the most short and shallow waters. Kraken aqua culture allows them to convert from hunters to agrarians.

Harbours dont exist except on landlocked lakes, neither do boats.

Human are confined to the continent they evolved on plus those with a land connection. (Australia and America's equivalents are never populated)

Human population are depressed without the sea as a reliable food source.

Kraken populations flourish inhabiting the Oceans from Poles to the equator. They can even tolerate fresh water for limited times meaning river are not safe for miles inland.

Krakens domesticate waterborne equivalents of Dogs, Cats and Horses. Think Dolphins and Whales as pets, guards and transport. Armies of Kraken can mobilise to cross large distances in short amounts of time. Sonar from trained whales is used to monitor regions near known human populations.

Kraken's discover selective breeding - plenty of options here - one example would be evolved Snapper & Mantis Shrimp as stun guns, Cone snails as assassins weapons.

Kraken's study hydraulics and hydrodynamics - meaning harpoons are developed with force and range several hundreds of meters from the shore.

Explosives may not be possible - but poisons and chemical attacks on harpoon warheads are.

Algae blooms are weaponised as mine fields.

Glass polishing develops corrective google allowing the Kraken to see in air.

Hydrogen is trapped from undersea vents or via electrolysis from specially bred electric eels. Kraken experiement with "lighter than water" craft - airmarines if you like.

TL;DR - You can play with Human development so it ranges from severely retarded or just mildly enough that air travel becomes risky.

if the krakens are intelligent, they'd realise that making sea travel impossible is a bad business model. if every schmuck who tries to sail gets eaten, nobody will sail and the krakens would go hungry. Maybe they'd establish a system whereby one out of every ten, fifty, a hundred voyages gets munched, enough to keep them going sustainably, but not so much as the humans invest in land travel

• If they are intelligent like humans, then the Tragedy of the Commons effect would likely still cause them to over-fish this valuable resource until it disappears. May 11 at 13:03
• If they were really intelligent, they'd realise that they were better off trading. They could allow safe passage, or offer to tow boats, in return for metal tools or other things they can't make underwater. May 11 at 14:37

They are very intelligent and evil, not simply clever, but able to understand patterns and develop plans to ambush and catch their prey, besides many other things (building, communicating, using tools, so on).

The kraken are very intelligent and EVIL. An evil creature will just attack and kill for fun, so I don't see why they wouldn't attack and kill human ships as long as they have the means to.

Sorry, mostly OT, but that much helium is an issue for other reasons. Yes, the helium will float away so, yes there will need to be a strong flux of helium from the planet to make such a large atmospheric component. The issue is that helium comes from radioactive decay of large atoms like uranium and thorium. If there's a lot of helium (and you're describing a lot of helium!), there's a lot of flux from the rocks, and there's a lot of radioactivity going on here on this planet.

But on the other hand, maybe all this radioactivity contributes to rapid mutations of the planetary life forms, and that's part of how the kraken got so big!

• You'll do better at answering science-based questions, maybe even the hard-science ones I suspect. As-is, this isn't a terribly good answer to the question with the tags it has (standards of analysis and evidence vary according to the tags attached) . Please take our tour and read-up in the help center about how we work, welcome to worldbuilding. May 13 at 3:24

## No

If Kraken are similar to giant squid, they'll:

1. be pelagic,
2. needs lots of room to maneuver since they're giant (meaning they won't get near shore), and
3. be relatively not numerous (since they'd be apex predators).

Since the oceans are Big, there won't be too many encounters. Encounters that do happen will be a "cost of doing business", just like storms.

Coastal trade will continue, and (eventually) large iron ships (to out-mass the kraken) and gunpowder will be developed; this means your "people" can fight back or even hunt them.

A potential alternative not mentioned by any of the other posters is that humans and krakens might end up coming into a symbiotic relationship. For example, killer whales and dolphins have been known to cooperate with humans to hunt larger whales (in the case of orcas) and fish, the orcas and dolphins herding the fishes and whales into the nets and spears of the hunters in exchange for eating some of the catch or the hunters leaving behind the parts of the whale carcass they cannot carry. In such a scenario with intelligent krakens, it's highly likely that the krakens learn they can get more by cooperating with human than destroying their ships.