They spend up to 16 hours a day in it - as a way to cool off. They live mainly in freshwater habitats, but populations in West Africa mainly inhabit estuarine waters and can even be found in the sea. They are not the most skillful swimmers - they swim at a speed of 8 km/h. Adults are also unable to float but only stand in the shallows. On the other hand, juveniles can stay afloat and often swim by making movements with their hind legs. They surface to take a breath every four to six minutes. The young can close their nostrils while submerged. The process of surfacing and breathing is automatic to the point where hippos surface without waking up, even while sleeping underwater.
