除了热喷口附近深海通常被认为是非常酷。For instance, water temps in the Mariana Trench (~10 km deep) are 1-4 °C. However, the geothermal gradient runs counter to that, where the lithosphere at the same 10km depth would be around 250-300 °C. So, in a sense, water should be heated from beneath and only be able to release its energy into the atmosphere/space. Yet, we see the exact opposite of this, where the upper layers are the warmest. Where did the thermal energy go? Is it the product of billions of years of ocean currents carrying the heat to the poles, or am I overlooking some other principle?