"Crabs who live by volcanic systems found along mid-ocean ridges - places where new sea-floor is created by the upwelling of magma."

Wikipedia - Everything you always wanted to know about Yeti crabs

BBC Science has a very interesting article about Yeti crabs who live 2,000 meters (6561 feet) down in a volcanic region of the Southern Ocean. BBC has a video of these creatures living by volcanic vents. I suggest go there and be amazed: Marvels of the deep and their superpowers

Kiwaidae aka Yeti crab aka Hoff crab