system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it skin have trouble differentiating between cold surfaces and wet surfaces when our eyes aren't looking?
gpt
Liquids conduct heat away from your body several times faster than air. Thats why falling into a cold lake, at say 40 F will kill a LOT faster than say being exposed butt naked to 30 F air. 

Cold surfaces do the same thing, conduct heat away. So if you're closing your eyes, all you feel is a loss of heat, since both cold surfaces and liquids do that, you have no way of telling.