"Fieldnotes," January 12th & 13th, 2014: "River Otters," by Beth Horn & Caroline Kurtz. http://www.montananaturalist.org/
"On bare ground, otters have a slow, awkward gait. But in soft snow they travel quickly in long glides on their bellies and often strike off for several miles across country. Otters sometimes use their slides to shoot themselves out into ice-free areas created by faster-moving water near the center of a stream. An otter can swim away under the ice, perhaps coming up nearly a quarter mile away."