system
Given the following post, respond as if you're commenting on Reddit:
human
[Subnautica: Below Zero] Sure is cold on this part of Planet 4546B. But why is it that the ocean's warm enough to swim in without getting hypothermia?

Is it because of all the geological activity, the physical properties of water, or what?
gpt
Wetsuit mechanics, mostly. You've got a very high quality futuristic wetsuit, but it's still a wetsuit - it can keep you warm in the water, but when you start to dry out, you will *freeze*. 

See, wetsuits work by keeping warm water inside them. A thin layer, warmed by your skin, to insulate against the cold water around you. This is why the sizing of a wetsuit is so important. You lose heat *much* more slowly in a properly fitted wetsuit in the water. But there's a reason people don't use this technique on land, and it's the same reason you freeze on the arctic surface of 4546B.