Ocean temperatureThe ocean temperature varies by depth, geographical location and season. Both the temperature and salinity of ocean water differs. Warm surface water is generally saltier than the cooler deep or polar waters; in polar regions, the upper layers of ocean water are cold and fresh. Deep ocean water is cold, salty water found deep below the surface of Earth's oceans. This water has a very uniform temperature, around 0-3 °C. The ocean temperature also depends on the amount of solar radiation falling on its surface.