The North American river otter (Lontra canadensis), also known as the northern river otter or the common otter, is a semiaquatic mammal endemic to the North American continent found in and along its waterways and coasts. An adult river otter can weigh between 5.0 and 14 kg (11.0 and 30.9 lb). The river otter is protected and insulated by a thick, water-repellent coat of fur.