It takes a lot of solar radiation to appreciably warm the ocean, but once it's warm, it can retain its heat energy for a long time.

Question

Quizplus · Accepted Answer

This is because water has a high heat capacity, which means it can absorb a lot of heat energy before its temperature increases significantly. Once it is warm, the ocean can retain its heat energy for a long time because water is also a poor conductor of heat, meaning heat doesn't transfer easily from the warm surface layer of the ocean to the cooler depths below.

It Takes a Lot of Solar Radiation to Appreciably Warm