Muskrat

Muskrats are rodents that live in freshwater and saltwater marshes, lakes, ponds, and streams. Muskrats often build dome-shaped houses in marshes. These houses, made of plants, protect the muskrat from predators, since the only entrance is underwater. Some muskrats live in burrows on the water banks. Muskrats are excellent swimmers but are slow on land. 
Muskrats are native to North America, but have been brought to Europe and Asia, where they now live in the wild. Muskrats got their name because they have musk glands that produce a strong scent.