There are several conditions which can make seawater more or less salty than normal.

1. Seawater tends to be less saline where there is more rainfall than evaporation.
2. The oceans are less saline near the mouths of large rivers where freshwater mixes with seawater.
3. The formation of sea ice leaves seawater more saline since salt is generally excluded from sea ice. Conversely, melting ice dilutes seawater with freshwater making seawater less saline than normal.