The most difficult salt riddles

Launched June 10, 2011, Aquarius is NASA’s first satellite instrument specifically designed to study the salt content of ocean surface waters. The complete first year dataset of NASA's Aquarius instrument reveals seasonal changes in the Amazon River's plume. Depending on the prevailing currents, the river's freshwater outflow heads east toward Africa or bends up north to the Caribbean.

With a salinity level of over 40%, Don Juan Pond is the saltiest of the Antarctic lakes. This salinity allows the pond to remain liquid even at temperatures as low as −50 °C (−58 °F) due to the interference of salts with the bonding of water molecules. Don Juan Pond was discovered in 1961 by George H. Meyer.

The Red Sea is very saline due to high evaporation, very little precipitation, almost no river inflow and isolation from the rest of the Indian Ocean. Salinity reaches 41 ‰ in the northern part (Average for the world's seawater is ~35 ‰).

The Arctic Ocean's salinity varies seasonally as the ice cover melts and freezes; but it is the lowest on average due to low evaporation and heavy freshwater inflow from rivers.