Freshwater seal

The freshwater seals are the species of seals which live exclusively in freshwater bodies.

The only true freshwater seal species is the Baikal seal.

The others are the subspecies or colonies of regular, saltwater, seals. These include the subspecies of ringed seal: Ladoga seal and Saimaa ringed seal.

Common seals are known to enter estuaries and freshwater rivers in pursuit of their prey. Colonies of common seals live in some lakes, such as seals of Iliamna Lake, Alaska, trapped there a long time ago. There is also a subspecies called the Ungava seal (Phoca vitulina mellonae) that comprises less than 300 individuals landlocked in the fresh water of Lacs des Loups Marins, Petit Lac de Loups Marins, and Lac Bourdel in northern Quebec.

...
Wikipedia