The American Water Shrew, Sorex palustris, is a large North American shrew found in aquatic habitats. Some sources include the Glacier Bay Water Shrew , S. alaskanus, within this species.

This animal is dark grey in colour with lighter underparts with a long tail. Air bubbles are trapped in the thick fur when the animal dives underwater. Its feet have a fringe of hairs, more visible on the larger hind feet, which allow this animal to run on the water's surface. Its body is about 15 cm in length including a 8 cm long tail and it weighs about 13 g.

These animals are found near streams and lakes along the Rocky Mountains and Appalachian Mountains and across Canada and the midwestern United States.

They swim well and make short dives in search of food. Their diet includes aquatic insects, small fish, tadpoles, slugs and snails. They are thought to use echolocation to help find prey. Predators include hawks, owls, snakes, mustelids and large fish.

These animals are active during the day but are more active at night. They are generally solitary and territorial except during mating. The female has 2 to 3 litters of 5 to 7 young in a nest in a tunnel or under a log. Water shrews typically live about 18 months.