Question: Hello! Why is the water at the bottom of the ocean cold even though it is close to the core of the earth (which I thought was meant to be hot!) Thank you(:

Cool question. Yes, things further down are hotter – in the earth. I imagine the rock at the bottom of the ocean, if you buried into it, would get hot. There are places where the lava does come and break through, like an underwater volcano, and the water boils. Those are called hydrothermal vents. The lava instantly turns solid because the sea is so good at cooling it.

But I think the ocean is very large (big volume) and there is no sunlight at all, so there is little warming it. The ocean carries heat away from the rocks (and has done for millions of years) so that would imply to me that the rock under the ocean is quite solid and quite thick. Nearer the surface, where it’s not cooled by water, the rock can stay hot and molten. There’s less of an insulating layer on land than there is in water where the rock is kept cold. That’d be my guess. The cold sea keeps a thick layer of insulating rock, meaning lava is closer to the surface of the rock where there’s land, which isn’t cooled so well.

Wonder if I’m right.