Although hippos are semi-aquatic, they cannot swim or float. Instead, they use their legs to push off from the bottom of the river and propel themselves forward.
Hippos have many adaptations for life in the rivers and lakes of their native Africa. Their eyes, ears and nostrils are on top of their heads, allowing them to breathe while remaining mostly submerged. They have clear membranes that protect their eyes while underwater. Hippos can fold their nostrils and ears closed and can remain under water for at least five minutes. Their webbed toes give them good support in shallow water. They even have a reflex that allows them to sleep underwater, causing them to rise up to take a breath every few minutes without waking up.