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Biggest icebergs have areas roughly similar to Crete and 500 meters thick, (https://en.wikipedia.org/wiki/Iceberg_B-15) I assume most of that thickness is hidden underwater, sadly I could not find answer to how high above the water was the actual biggest iceberg recorded. Icebergs, being made of ice, do not survive well in hotter climates and often break into smaller parts. My idea is: create an iceberg out of pykrete (https://en.wikipedia.org/wiki/Pykrete) to decrease the melting problem, add internal tunnels with cooling equipment and structural support for the gigantic structure, and then, cover the iceberg with soil, rocks, trees, small hills, houses, everything you could find on a normal island.

I need to know if such island would be physically possible to build and if you could build an entire self contained ecosystem on its surface.

Edit: If you think other materials are fit to fulfill the requirement of making Crete-sized floating island, I am open for suggestions.

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    $\begingroup$ I'm intrigued by the idea, but is a frozen material a requirement? Modern ships are made of steel, which is much heavier per cubic meter than ice or Pykrete, proving that if you displace enough water, anything will float. Why Pykrete with all its cooling equipment in the Mediterranean (as an example), when you could simply use concrete (Roman concrete gets harder in salt water). This is especially important as the surface you're covering with top soil is frozen, causing all kinds of ecological problems. $\endgroup$ – JBH May 22 at 22:44
  • $\begingroup$ @JBH Pykrete was my first thought, as it was suggested for giant carriers during Second World War (Habbakuk Project), and when I noticed the sizes of biggest icebergs I kinda connected the dots here. I am open to different possibilities though, if making floating islands of similar size is doable with concrete, I will be happy too. About the problem of soil lying on cold ice, perhaps covering the whole island with some kind of insulation would help? $\endgroup$ – Mranderson May 22 at 22:49
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    $\begingroup$ My guess is that it was suggested during WWII because it was cheap at a time when steel was in high demand. OK, let's stick with Pykrete (I'll be curious to see what people have to say). I'd add the reality-check tag and modify the edit to suggest something like, "if you want to suggest a Frame Challenge in favor of another material..." I don't want the question closed as too broad or primarily opinion-based. $\endgroup$ – JBH May 22 at 22:56
  • $\begingroup$ @JBH I am not familiar with most of SE features as I use it not often enough, but I think the one edit I made fits into the "frame challenge", permitting answers with alternate materials, thanks for the trouble though! I will get sleep and come back in the morning to check how is it going on here. $\endgroup$ – Mranderson May 22 at 23:28
  • $\begingroup$ A series of concrete spars could be linked together to form massive platforms, no ice needed. $\endgroup$ – GrandmasterB May 23 at 21:14
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You can but it is not a permanent structure, it is also a huge waste of money

Pykrete dramatically slows melting but it does not stop it, and nothing you can do will stop it entirely just due to osmotic imbalance, so you bases starts shrinking from day one. That said you can probably get several years of use out of it, if you keep it in cold waters and build it as a solid iceberg, but that is not much compared to how much it w cost to build it. You would be better off building it out of floating foam concrete. It will cost more but will last a lot longer and you can build structures in it.

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The square/cube law is working in your favor, in this case. If you get the initial freezing done for free (assemble in Antarctica), and you go well below the melting point of ice in that initial freeze, you now have a ginormous heat dump (size cubed) with a just-enormous area to receive heat (size squared) you can use passive heat- (well, in your case cold-)pipes to keep your surface a smidgen below zero, ever so slowly heating the deep-frozen core.

As an iceberg the size of Crete would be about 20000 times bigger than the prototype pykrete ship, you can expect it to last longer than recorded history.

PyCrete!

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There is no need for the island to be made entirely out of a single material

Filling it with air pockets(caves) should help with many problems. There are caves even inside icebergs, so this is not that strange. Those air pockets will help with the floating part (letting the island have more heavier-than-water things), and those caves can serve as habitats for many species (humans included).

Caused by a higher oceanic temperature, water currents or the ocean composition (saltwater), the biggest problem for using pykrete, ice or any ice-based material is that it will eventually melt outside Bellow-zero temperature, and any melted ice in contact with the salty ocean goes away, never coming back. Having those air pockets gives you more options to protect the submerged part of the island from water itself using any viable material (thermic insulation or hydrophobic behavior).

There could be "island-sized" ships made out of many materials, but the question specified a pykrete-based island. There can even be a super-sized fire ant island, as they can be treated as a solid-fluid material, with measured properties like elasticity.

And, is this island to be piloted/guided like a ship or Just let it drift in the ocean?

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  • $\begingroup$ Sorry for inactivity under my question, I didn't think about island's propulsion yet and I am not sure if there will be one. $\endgroup$ – Mranderson Jun 7 at 12:39
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Not possible

Crete is around 8500 square kilometres so the surface area is going to be a lot bigger than that for an iceberg considered 90% will be underwater.

The cooling needs is mind blowing so suddenly you need to generate the energy to cool it and a way of getting rid of the waste heat from both the island and the multiple massive nuclear reactors needed to power it all.

How do you get rid of that heat without having that heat melt the island let alone environmental heat?

Water is an excellent conductor of heat so it will eat away from the island better than air. Pykrete will slow it down but cannot stop it.

Better to build the island from styrofoam.

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  • $\begingroup$ A watertight seal would be needed on the styrofoam, so water doesn't seep in and sink our floating Crete. Also, a quick back of the envelope calculation suggests that even a 10 meter thick styrofoam island could support 80,000 tonnes of weight, or about the weight of 1,600 houses. Of course, waves would be a different issue. $\endgroup$ – Cloudy7 May 24 at 4:30
  • $\begingroup$ Still a fraction of the size of an iceberg. $\endgroup$ – Thorne May 24 at 10:55

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