Rhinos are excellent swimmers, according to the World Association of Zoos and Aquariums. They can also dive and feed under the water and spend approximately 60 percent of their time relaxing there. Water is essential to rhinos, as it protects against parasites and ensures adequate body temperature. Rhinos are water-dependent and typically consume water on a daily basis, but they can survive for several days without water if the supply is scarce. Rhinos roll around in watering holes in order to cover themselves with mud, as mud offers protection from biting insects and parasites. Mud also creates a natural sunscreen, protecting the rhino's thin outer layer of skin.