system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If heat spreads evenly through liquid, why are there "warm waters" and "cold waters" in the oceans that are all connected?
gpt
It does not do so instantaneously. And you have different levels of eat influx at different locations. Then you have the effects of salinity causing very noticeable difference between layers of water. And finally, you have water currents.

The ocean is not homogenous.