Who would have thought that those cute little creatures flipping around in the water off North America's west coast are crucial to the region's underwater ecology? As sea otter expert Jane Watson tells us, they don't just live in the ecosystem, they practically run it. Watson has watched sea otters around Vancouver's Bunsby Islands for years now. She's seen their population spread out along the coast--and she's observed majestic underwater forests of kelp that spring up wherever the otters appear. Otters were once viewed as a threat to local fisheries, and they were nearly hunted into extinction. But through her research, Watson has shown that lots of healthy otters mean lots of fish and vegetation. Join Jane Watson as she dives through the deep and learn the mysteries of the only mammal to have re-evolved for life back in the ocean.