The short, rather weak limbs have five nonwebbed digits. A longitudinal flange of skin is present along the inner border of the hind foot, so that it may be pressed smoothly against the body and tail in swimming. The tail seems to be the only means of propulsion in the water. On land this animal walks on the soles of its feet, with the heels touching the ground. The two lower bones of the hind leg are united distally.
Females have two mammae located in the groin region.
Habitats include both sluggish lowland streams and cold, clear mountain torrents, from sea level to about 1,800 meters. It is an extremely agile and rapid swimmer. It becomes active in the late afternoon, after sheltering during the day in holes and tunnels in stream banks. The entrance to its burrow is below the water level. On land its movements are rather clumsy, but it can move at considerable speed.