A brine pool is a large area of brine on the ocean basin. These pools are bodies of water that have a salinity three to five times greater than the surrounding ocean. For deep-sea brine pools, the source of the salt is the dissolution of large salt deposits through salt tectonics. The brine often contains high concentrations of methane, providing energy  to chemosynthetic animals that live near the pool. These creatures are often extremophiles. Brine pools are also known to exist on the Antarctic Shelf where the source of brine is salt excluded during formation of sea ice. Deep-sea and Antarctic brine pools can be toxic to marine animals.