The Glacier Bay water shrew (Sorex alaskanus) is a species of mammal in the family Soricidae.

It is endemic to Alaska in the United States.

[1] It can swim underwater, and when it stops swimming, air trapped in its fur lets it float back up to the surface.

Its fur is water resistant, although if it does get wet it returns to shore to dry itself with its hind feet.

It eats aquatic fly nymphs and terrestrial invertebrates.