hippopotamus under water enjoying his day and relaxing

Hippo under water
Hippos can even sleep underwater, using a reflex that allows them to bob up, take a breath, and sink back down without waking up. Yet despite all these adaptations for life in the water, hippos can't swim—they can't even float!

Hippos cannot swim very quick underwater but still, they can swim at a speed of 5 mph (8 kph) and also walk underwater.

They propel themselves underwater using their legs to propel themselves forward. Their high body fat also assists with their buoyancy.” Hippos do not swim as humans or other animals do, but generally walk underwater occasionally propelling themselves off the ground or other surfaces