In this picture, we see a futuristic cityscape, with what seems to me an unexpected occurrence: a fairly normal-looking barge chugging along down the river! That just looks out of place, and it brought to mind my question.

In ~500+ years, will we, or I suppose any other civilization with similar planets and technology, require vehicles for human travel or goods transportation that are bound to rivers and such? They are mostly used now due to large cargo space available per ship, and cheapness compared to air, but I would have thought that in a situation depicted here, we would by then have advanced past the slow, location-constrained, water-based methods. But assuming I'm wrong, what would be the reasons for this tech still to exist in the far future, beyond the occasional tycoon's pleasure cruise?

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    $\begingroup$ It would be large cargo available per ship, and cheapness compared to air, maybe? $\endgroup$
    – SJuan76
    Commented Feb 2, 2015 at 20:51
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    $\begingroup$ Today we ship by water. 500 years ago we shipped by water. 500 years before that we shipped by water. 500 years before that we shipped by water. Its a good bet 500 years from now we still will. $\endgroup$ Commented Feb 2, 2015 at 21:03
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    $\begingroup$ @GrandmasterB Though I don't disagree with the conclusion, your logic is terrible. You could replace 'shipped by water' with 'have not landed people on Mars' and there is no reason it should be a good bet to be true. $\endgroup$
    – Samuel
    Commented Feb 2, 2015 at 21:14
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    $\begingroup$ @Samuel The point is water transport has proven itself to be a cost effective form of transport for thousands of years, and the default position should not be "why would we still use it", but "why wouldn't we still be using it". I can see reasons why we wouldn't use it... but they'd have to be pretty extreme technology and energy changes. $\endgroup$ Commented Feb 2, 2015 at 21:31
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    $\begingroup$ @GrandmasterB I agree completely. I was just disagreeing with the apparent reasoning. It was presented as 'this is how it's always been done, so we will continue to do it.' $\endgroup$
    – Samuel
    Commented Feb 2, 2015 at 22:12

11 Answers 11


We'd send things by ship for the same reason we do today. It's cheap. It's not likely that individuals, corporations, or governments of the future would not be motivated by the cost savings associated with transport by ship.

Unless there is some magical energy source in the future that makes energy free, or nearly free, in terms of monetary and environmental costs we will likely always use waterways where possible.

Without this energy source, it may be that, after peak oil, fuel will be so expensive that transporting cargo by aircraft will be prohibitively expensive. So people of the future will look at photos of cargo planes and think that we are the crazy ones.

  • $\begingroup$ This. In fact, put in a nice header: We're the Crazy ones (or out of historical sync). $\endgroup$
    – user3082
    Commented Feb 2, 2015 at 21:30
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    $\begingroup$ Water does the work. $\endgroup$
    – James
    Commented Feb 2, 2015 at 21:59
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    $\begingroup$ And regarding 'free energy that would replace shipping by water'...note that for a few thousand years, shipping by water was using free energy: wind. $\endgroup$
    – DA.
    Commented Feb 2, 2015 at 23:53
  • $\begingroup$ We still ship things today by horse and carriage in some parts of the world - even in fairly large cities. When I visited China, it was quite common to see people transporting things by bicycle in large cities. Assuming boats in the future aren't just for pleasure purposes, I could see it still being economical for many. So I agree with this answer. $\endgroup$ Commented Feb 4, 2015 at 22:07
  • $\begingroup$ @DA: and it may in the future! Research is being done in using large kites / parafoils with computer-controlled lines to augment the traditional engine power used in cargo shipping. $\endgroup$
    – Wingman4l7
    Commented Dec 16, 2015 at 21:16

Even if we do create a free energy source, heavy freight will still be transported by water because it is safer.

With free energy, we probably could transport massive items by air, but the risk to those living under their flight plans would be unreasonable. One faulty circuit which blows at the wrong moment, and thousands of tons of freight could be returning to earth violently.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – user
    Commented Feb 4, 2015 at 18:13
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    $\begingroup$ To summarize (the fun) discussion over in chat: today, plane travel is actually safer than travel by ship. There doesn't seem to be evidence that this would change in the future, nor does it seem that the minuscule difference in safety between the already safe shipping methods of both sea and air would be a significant reason why we wouldn't still do both. $\endgroup$
    – DA.
    Commented Feb 5, 2015 at 1:36
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    $\begingroup$ Air transport is also a lot louder. $\endgroup$
    – orkoden
    Commented Feb 16, 2015 at 19:14

Why would we not be using water transport in 500 years' time? Ships are an extremely efficient way of transporting large volumes of non-time-critical cargo. They also require relatively little infrastructure: if you're using the ocean or rivers, you really only need a place to park the ship and equipment to load and unload it at each end of the journey. (The same is true of planes but not trucks or railways.)

So maybe we won't care about energy efficiency very much when we finally invent that "free" energy source (e.g., fusion power). Well, that isn't necessarily the case. Perhaps the "free" power relies on economies of scale. Maybe we can sensibly build fusion power stations for cities but not for "small" things like ships and aircraft. That's basically what happened with (fission) nuclear power: only a handful of nuclear-powered cargo ships were built, even at the time when nuclear power was the sexiest thing going and we weren't very worried about radioactive waste and so on. Even with miniaturized free power, it might still be cheaper to put all your stuff in a ship with a big diesel engine and a few crew (or even totally automated) and wait a few weeks.

And if we're not using water for bulk transport, it seems we'd have to use the air. But air travel really isn't suited to bulk transport. One of the standard, large-ish sizes of ocean-going bulk ship carries about 50,000 tons of cargo. Suppose you had a "free" energy source and you put that cargo in a plane instead. First, it has to take off, by forcing enough air downwards that the force exceeds the weight of the craft and its cargo. Better not do that near any population, because the downdraft and noise are going to be extremely destructive. Now suppose we're airborne. 50,000 tons moving at 100 metres per second (about 225mph) at 30,000ft has about 2.5x10^11 joules of kinetic energy and 5x10^12 joules of potential energy. That total amount of energy is about one seventeenth of the energy released by the Hiroshima bomb. From time to time, these things will fall out of the sky. When that happens, they will make a big mess on the ground. And note that one of the reasons air travel is so safe is that there are a lot of airports around so, if something goes wrong, a plane can divert to the nearest suitable airfield (or not-so-suitable airfield or even not-an-airfield-at-all if the situation is urgent enough). Because of their need for specialist facilities, giant cargo planes would be much more limited in their ability to divert.

Finally, you may be underestimating how much freight travels by ship today. It's easy to imagine shipping as being something mostly from the past but it emphatically is not. Just think of the amount of "Made in China" stuff you see in the shops. All of that came by ship. All. Of. It. The plastic all that stuff is made from? That's made from oil that was mostly transported by ship. Or it's recycled from waste that was transported by ship. (Quite a large fraction of what those container ships take back to China is waste plastic for recycling, rather than just sending back empty containers.) You see those cars on the road? A good fraction of the steel in them was made from iron ore that was transported by ship. Huge amounts of grain are transported around the world – by ship, 50,000 tons at a time.

  • $\begingroup$ "From time to time, these things will fall out of the sky. When that happens, they will make a big mess on the ground." Of course with 'free' energy it would be pretty simple to mitigate against this. $\endgroup$
    – NPSF3000
    Commented Feb 5, 2015 at 9:18
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    $\begingroup$ @NPSF3000: How so? $\endgroup$ Commented Feb 5, 2015 at 13:09
  • $\begingroup$ @LightnessRacesinOrbit if you have free energy, then many things that are currently cost prohibitive are not. For example, you would likely have redundant engines, fail safe designs and backup machines that 'catch' falling machines etc. Furthermore you could stop the problem at the root cause, if a single 50,000 ton transport is too risky, why not break it up into 10 kilo units and fly over less sensitive terrain. $\endgroup$
    – NPSF3000
    Commented Feb 5, 2015 at 13:14
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    $\begingroup$ @NPSF3000 Your belief that arbitrarily low failure rates can be achieved just by adding another layer of redundancy is unrealistic. Any system can fail and failures are often correlated: if the engine and parachute each fail one time in a thousand, the system fails more often than one time in a million because, e.g., the engine exploding will take the parachute with it. Two once-in-a-thousand parachutes fail more often than once in a million because the same conditions (tumbling drone, high winds, whatever) that caused the first to fail also cause the second to fail. $\endgroup$ Commented Feb 6, 2015 at 9:06
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    $\begingroup$ @DavidRicherby - Evidently the web announcement I read was misdated. Interwebs fayl. $\endgroup$
    – JohnP
    Commented Feb 6, 2015 at 21:04

If we look at the imaginations of futurologists of yesteryear, and their expectations of what we'd have today, two things stand out, at least to me:

  • They were wrong about the cool stuff that they expected would be commonly used by everyone. Meals in a pill, robot maids, flying cars, jetpacks, supersonic trains and planes, moving sidewalks, weather control, rotating space stations with artificial gravity, moon stations and so on.

  • They were wrong when they were right. When Flash Gordon leaps out of the spacecraft he clips on his little levitation belt instead of a parachute, and grabs the briefcase-sized communicator radio. The videophone is not wireless, but rather built into the wall of a house, with a CRT and everything.

So, in general, it seems best, when looking at the past, to assume that things will NOT change, unless there's a clear sign that technology must inevitably change things. What technology could come along that will make shipping obsolete? Better roads?

But if the factories already exist by the rivers/dams for cooling, and for proximity to power generation, surely the rivers will remain the best way to get the materials to the factories, and to get the output away?

Any visit to any lake or beach in the US on the weekend will tell you that there will never, ever be a day, in any conceivable future, where pleasure craft will be obsolete. Instead, what we can guarantee is that the existing plethora of designs will be joined by newer ones as the tachnologies advance. But there'll still be people who like a sailing dingy, or a kayak, not because, nowadays, they are any more practical than an inflatable dingy with an outboard motor, or a jet-ski, but because they are more pleasurable. These places, as populations rise, just become more teeming with craft, not less.

Same with cruises, and yachts.

So if shipping, cruises, yachts, and small recreational craft still exist, what does that leave, to get rid of?

Passenger craft is one - in Bangkok, taxi-boats ply the canals, but they wouldn't be needed if the canals were paved over. But why would people do that? The canals bring business and shipping and look nice and provide drainage in floods. So, odds are the small canal-taxis will continue to exist, even if their drivers become automated.

Ferries are still used where there are no toll-free tunnels or bridges, and people want to take something heavy, like their car, to their destination.

What about larger passenger ships? Well, long distance, that service has by and large been replaced by planes already. People coming to the US from Europe now fly, rather than take a ship.

Overall, I can't see any technology which will further remove water craft.


the reasons for this tech still to exist in the far future, beyond the occasional tycoon's pleasure cruise?

That line, I realized, was the one that felt most wrong to me. It doesn't work like that. Stuff gets cheaper. That swarm of pleasure craft is only going to get bigger as materials science and manufacture get more advanced and the craft become cheaper. Why would water ever become the domain only of "tycoons", rather than the birthright and pleasure dome of everyone who lives nearby?

Perhaps if laws are passed to protect the water from the people - but even then they'll sneak in.

Perhaps if the waters became dangerously polluted, then at least fishermen might no longer take to sea, and people wouldn't swim in it any more... but even then, people would cruise upon the waves, just not swim in them.

As it becomes more crowded on land, the space and freedom of the open sea will become more and more intoxicating, and more and more people will be pushed to live there, some permanently. It's a valid solution to overpopulation. Sure, the wealthy might have their own ships, but link together a long enough bunch of cheap rafts connected with dynamos, and the wave power can generate electricity for the community. Who needs to be rich?]

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    $\begingroup$ Pleasure domes! Stately pleasure domes! ++! $\endgroup$
    – Willk
    Commented Jul 22, 2017 at 0:42

I'll open with a quote from Donald Knuth:

Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

What he means is this: say you're carrying a box of 100 4TB hard drives. Say you're traveling at 60mph. Your data transfer rate is ~1500TB/1.6s. Consider that your best download speed MIGHT be on the order of 2-3MB/s then you'll understand why his joke... isn't a joke.

The biggest reason why (in terrestrial environments) you'll never see barges go away is that even assuming massive gains in energy efficiency, it still takes more energy per unit of mass to make a plane fly than it does to make a barge move in the water. Which then also means your fuel cost for a barge will be cheaper thus making it a preferred method of hauling cargo. We will never see planes capable of taking on the kinds of cargo payloads that modern freighters get on the open seas and rivers.

For comparison, the [largest cargo plane in the world] can only haul 209tons. Compare this with the new freighter just launched that can hold 19,224 67,200lb containers. To convert that for you, that's ~644004 tons.

[These were my original numbers. These will have to be adjusted as noted from a comment:

The numbers in this post are misleading. The max deadweight tonnage of the new ship MSC Oscar is 197,000t (source: Wikipedia; "deadweight" is the total amount of cargo, fuel, crew, supplies, etc. that can be carried). Also, while 67,2000lb containers are available, a standard 20ft container is only specced for 53,000lbs. As you can see, MSC Oscar is specced for an average weight of 197,000*2000/19224=20,500lbs per container. There are strict limits to how many "heavies" can be carried and where they can go in the hull. – @David Richerby

The actual tonnage capacity is 197k, however even being ~3x smaller than my original numbers, you're still talking several orders of magnitude of capacity difference between jets and barges.]

Even assuming cheap and abundant energy, the energy efficiency per unit of mass simply cannot be matched. An advanced futuristic society is going to understand this.

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    $\begingroup$ Note, for example, that Airbus, a company, which literally gets airplanes for free, has purpose-built cargo-ships and designed a very elaborate transport route to ship A380 parts around Europe. They do have the Beluga, but it can only carry fuselages of smaller aircraft (not the A380) and some smaller parts of the A380. $\endgroup$ Commented Feb 3, 2015 at 20:05
  • $\begingroup$ +1 for the Knuth quote, and a sadly-virtual second +1 because of giving numbers that really show the difference. Just for safety, I would hope that an advanced society wouldn't put 2/3 of a million tons of low-priority materials into the air even if it was economically and environmentally feasible to do so. $\endgroup$ Commented Feb 4, 2015 at 7:27
  • $\begingroup$ I thought about broaching Peak Oil in my answer but more or less erred on the side of "Q wasn't really talking feasibility." That said, the fuel needed to match the biggest container ship in the world would almost equal the weight of cargo. (Airmchair estimate.) $\endgroup$
    – avgvstvs
    Commented Feb 4, 2015 at 18:31
  • $\begingroup$ @JörgWMittag Airbus emphatically does not get airplanes for free. Every regular airplane that airbus builds and uses for itself would be tens to hundreds of millions of euros of lost sales (list price is about \$70-100M for a narrow-body and \$200-380M for a wide-body). For special-purpose planes, you have all the design, testing and certification costs. The fleet of five Belugas cost nearly \$1.5 billion between them. $\endgroup$ Commented Feb 6, 2015 at 9:31

A lot of the answers here theorize about "When tech catches up", but remember there is many researches going on in the water craft area, when a plane becomes more efficient, the ships also becomes more efficient.

Powerful computers are used to calculate hull designs that is more aqua-dynamic. Engines are becoming more efficient, and motors are attached to convert wind and solar power to propulsion.

On ships there is installed computers with large servers that constantly feels the water, current, waves, wind and a lot of other aspects with high tech sensors, to make the travels faster and more efficient.

I therefore i think that it will take many more years than just 500 for other technologies to catch up with the water transportation.

Maybe if the polar caps melts, waterways would be even more attractive.



Besides being cheap and power efficient as most answers point out, currently most large cities are in river deltas. Therefore there are often ports to connect the cities to global trade routes. The rivers allow transporting goods to inland cities. And historically river delta cities had canals for transport within the city (for example Venice and Amsterdam).


They are mostly used now due to large cargo space available per ship, and cheapness compared to air, but I would have thought that in a situation depicted here, we would by then have advanced past the slow, location-constrained, water-based methods.

Have you looked at the image? Where are these large scale air transports?

Instead all I see is a very limited number of small aircraft that appear to have considerable resources spent into minimising weight and maximising aerodynamics - not exactly a sign of cheap air travel.

Heck I even see windmills, which unless they are there for purely aesthetic or historical reasons indicate that the energy generation capabilities have not changed significantly.


A slightly longer response to a reply:

You could replace 'shipped by water' with 'have not landed people on Mars' and there is no reason it should be a good bet to be true.

This is a disingenuous reply. Things we have done that we're no longer doing, versus things we've never done but are technically feasible.

We don't really ship by barge now. Erie Canal? D&H Canal? Superseded by railroad.

We will ship by sea, until there is a safer and cheaper technology. Nothing we've developed yet comes anywhere close to that mark.

We have taken the 'move by water' to the limits of what's accessible, and it costs too much to dig canals, compared to laying track (and railroad goes over or through mountains, and has a really nice network, at least in the US: home to 50% of all the track in the world, iirc).

Trans-shipping from big ships to smaller ships costs as much as trans-shipping to railroad, so we aren't doing barges (right now), and we won't in the future - if we continue to have the diesel to run the trains with (see peak oil). But we will be using ships, and we will still be using rail, until that mythical, cheap antigravity drive up-ends our technological transportation structure.

If we could move earth quicker, and more safely, and line canals - we might put sea access in a lot more places. But it would be huge waterways, that would handle Malaccamax, Chinamax or Suezmax sizes of ocean-ships, not smallish barges. And we might not even then, because unloading a huge ship requires some huge cranes and port facilities. Which is probably why a number of ports are having issues.

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    $\begingroup$ There is a significant amount of barge traffic on US river ways today. Grain exports for example. It may not be as common as it once was but it is still cheap and easy. $\endgroup$
    – James
    Commented Feb 2, 2015 at 22:02
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    $\begingroup$ Echo James...not sure what cities you are in @user3082, but the pub I frequented in university received it's stock via a monthly barge. Along existing larger waterways, barges are superior to trains, no? $\endgroup$
    – Twelfth
    Commented Feb 2, 2015 at 22:22
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    $\begingroup$ The Mississippi is full of barges. $\endgroup$
    – DA.
    Commented Feb 2, 2015 at 23:56
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    $\begingroup$ The Erie Canal is still used regularly to ship cargo $\endgroup$
    – Johnny
    Commented Feb 3, 2015 at 0:04
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    $\begingroup$ We're still building canals even today. $\endgroup$
    – DA.
    Commented Feb 3, 2015 at 14:59

Tugboats pushing little barges down little rivers in a futuristic city is incongruous. Especially when there are no levees to protect against flooding.

Big tugboats pushing huge sets of barges down large rivers will still be quite common, though.

EDIT: "little barges" have been replaced by trucks and paved roads. The "huge sets of barges" on "large rivers" will still be there for the same reason that others have stated that cargo ships will still ply the oceans: cost when moving bulk goods and speed isn't a priority.

  • $\begingroup$ Care to expand on your logic behind this? I'd love to hear more from your position $\endgroup$
    – mjr
    Commented May 10, 2017 at 6:15

The fact that we would still be living on the earth 500 years later is almost impossible. Computation power is increasing at an unprecedented rate, and we might be living perfect lives 500 years from now. This article shows us that 500 years is far too wide a timespan to start predicting. For example, for a person living at 1515 AD, the concept of even hovering over the ground was unthinkable, today Voyager satellites are progressing to leave the solar system. The rate of linear growth in technology is growing, and I see nothing wrong in another hypothesis that we would be storing and using all the water available to us, on some place other than the earth. Maybe 50, or at the most 100 years would be a more realistic question to ask.

  • $\begingroup$ "The fact that we would still be living on the earth 500 years later is almost impossible" I agree. I mean thousands of years ago there were some barbarians in Britain. Over time, with advancement they managed to conquer nearly a quarter of the entire world. Today, they don't even live there! $\endgroup$
    – NPSF3000
    Commented Feb 5, 2015 at 9:15
  • $\begingroup$ I think Leonado had this one designed well over 500 years ago -- leonardodavincisinventions.com/inventions-for-flight/… $\endgroup$
    – Soren
    Commented Aug 26, 2015 at 0:41

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