Freshwater freezes faster that saltwater, according to the National Oceanic and Atmospheric Administration. Freshwater freezes at 32 F, while saltwater freezes at a slightly lower temperature, 28.4 F.
When saltwater freezes, the salt and water actually separate from one another. For the most part, only the water freezes. For example, if frozen ocean water is melted, it contains very little salt and is usable as drinking water. About 15 percent of the world's oceans are covered with ice at some point during the course of a year. The average temperature of all ocean water the world over is 38.3 F.