Northern River Otter
The Northern River Otter is a semi-aquatic carnivorous mammal in the weasel family. In Virginia, river otters inhabit a variety of habitats along rivers, lakes, streams, marshes and coastal shorelines. Otters are mostly active at night, or at dawn or dusk.
Supremely adapted for an aquatic lifestyle, river otters have a powerful, rudder-like tail and webbed feet. Able to close off their short ears and nostrils while swimming, and having additional eye covers called “nictitating membranes” that act like “swim goggles” to protect their eyes.
Otters can swim underwater for up to 4 minutes, swim at speeds up to 6-7 mph, and dive as deep as 55 feet.
Information from Virginia Living Museum.