User blog comment:WolfgangBSC/The Random Chat Room/@comment-24938973-20151202183017/@comment-27797576-20151202202705

Yeah, but water is an exception to the rule. Water, momentarily before it freezes, expands. Why do you think ice floats in water, and always will? It's certainly not because of any chemical change, it's still water. And if it did contract, it would be denser than water, or neutral to water(most likely this), but then it wouldn't float. Because of the shape water takes when it cools, it actually expands when it forms a solid, which is why ice is less dense than water. Now as I said, that's what happens in Earth's atmosphere(aka 1 earth atmosphere). I forget what happens to ice when it's below earth's atmopheric pressure. But yeah, the area where the water is going to be is the area where it melts, more or less. It's not going to move anywhere unexpected, and it's certainly not going to do what harmon's pic he showed once(the deviant art one), which covered half the entire planet and the south pole still had frozen ice and dry ice, which IIRC, would have melted. In fact, the water might even take up less area, but that all depends on how the water reacts to the low atmospheric pressure.