system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: if we have same tempature water and air, why does the water feel colder to the air when we go for a swim for example?
gpt
Water transfers heat faster than air does.  Your skin feeling hot or cold, is more about the rate of heat transfer than it is the temperature itself.  So jumping in cold water quickly draws a ton of heat out of your skin, making you feel a lot colder than in air.