Hands-on activity on sea water salinity

In the first lecture of the “introduction to oceanography” GEOF130 course 2013, we investigated water samples from four different regions: The Mediterranean, the tropical North Atlantic, the Baltic and Arctic sea ice. Just by tasting their different salinities (40psu, 35psu, 10psu and 5psu, respectively) students figured out which of the samples came from which region. And now what influences salinity in the ocean?