On average, ocean water is about 3.5% salt solution. This usually depends on latitude, evaporate rates, and connections to other bodies of water. The Atlantic Ocean is the saltiest out of all of the major oceans; its salinity can reach up to 3.7%. There are other bodies of water that are much greater in salt concentration than that, like the Dead Sea (near the Mediterranean) and Lake Assal (in Africa), which have salt concentration levels up to 34%. When water is this salty, you can float very easily in it!