Squirt here to talk about how temperature changes in the water column. The surface waters (epipelagic layer) tend to be warmer than deeper waters because they are warmed by sunlight. The bathypelagic layer feels very cold to me. I live happily in the mesopelagic layer because the waters are just right. Other factors that affect water temperature are longitudinal location and water currents. Waters closer to the poles are colder than waters which are close to the equator. Have you ever seen pictures of the Southern Ocean? There are usually chunks of ice floating. Brrr... I don't think I like the cold waters at the poles! Do you like the cold?