Deep ocean water
Deep ocean water is the name for cold, salty water found in the deep sea, starting at below the surface of Earth's oceans. Ocean water differs in temperature and salinity. 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 makes up about 90% of the volume of the oceans. Deep ocean water has a very uniform temperature, around, and a salinity of about 3.5% or, as oceanographers state, 35‰.
In specialized locations, such as the Natural Energy Laboratory of Hawaii, ocean water is pumped to the surface from approximately deep for applications in research, commercial and pre-commercial activities. DOW is typically used to describe ocean water at sufficient to provide a measurable difference in water temperature.