Why doesn't deep sea water freeze?

Basically, this lowers the freezing point of ice, which means water can be below 0 Celsius at the bottom of the ocean and not turn into ice. Actually, the main reason water doesn't freeze at the bottom of the ocean may be that it rarely gets that cold down there. Water freezes at normal pressures (on land, at sea level) at zero degrees Celsius. read more

Deep sea water has a much higher concentration of salt compared to surface water. Salty water (Brine) lowers the freezing point of water. In addition to this, The many salts found in ocean water are more dense than water, they sink and thus push the less salty water up in the ocean. read more

When seawater freezes, however, the ice contains very little salt because only the water part freezes. It can be melted down to use as drinking water. At least 15 percent of the ocean is covered by sea ice some part of the year. read more