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

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 bodies.

The only true freshwater seal species is the Baikal Seal.

The others are the subspecies or colonies of regular, saltwater

Seawater

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

, seals. These include the subspecies of Ringed Seal

Ringed Seal

The ringed seal , also known as the jar seal and as netsik or nattiq by the Inuit, is an earless seal inhabiting the Arctic and sub-Arctic regions...

: Ladoga Seal

Ladoga Seal

The Ladoga ringed seal , is a freshwater subspecies of the ringed seal which are found entirely in Lake Ladoga in northwestern Russia. The subspecies evolved during the last ice age, about 11,000 years ago...

 and Saimaa Ringed Seal

Saimaa Ringed Seal

The Saimaa ringed seal The Saimaa ringed seal The Saimaa ringed seal (Pusa hispida saimensis, is a subspecies of ringed seal (Pusa hispida). They are among the most endangered seals in the world, having a total population of only about 260 individuals. The only existing population of these seals is...

.

Common Seals are known to enter estuaries in pursue of their prey. Colonies of Common Seals live in some lakes, such as seals of Iliamna Lake

Iliamna Lake

Iliamna Lake or Lake Iliamna is a lake in South-West Alaska, at North end of Alaska Peninsula, between Kvichak Bay and Cook Inlet, West of Seldovia, Alaska Bristol Bay Low....

, Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

, trapped there long time ago. There is also a subspecies called the Ungava Seal

Harbor Seal

The harbor seal , also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere...

 (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

Quebec

Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

.