The North American River Otter (Lontra canadensis), also known as the Northern River Otter or the Common Otter, is a semi-aquatic mammal endemic to the North American continent, found in and along its waterways and coasts. An adult river otter can weigh between 5 and 14 kg (11 and 30 lb). The river otter is protected and insulated by a thick, water-repellent coat of fur.