Great question, easy answer! Watch the following video to find out! 
Broadcaster: BBCWorldwide
Funny fellows aren’t they?! They almost remind me of manatees when underwater.
Do you get it now? These beach boys can literally walk on the river bed! And while they advance, they look like running horses in slow motion. Or perhaps weird astronauts on the moon… 
What really amazes me is that they can float when desired, and also sink as easily…with no effort whatsoever! Really cool, especially when you consider their average mass (1700 kg)!
Tags: hippo, hippo video, river horse
That's cute. I find it fascinating that the hippo can make noises like that underwater while holding their breath. I'm lucky if I can hold my breath for 1.5mins. 6 mins is amazing.
Baby hippo doing the sumersault – adorable!
You would think with the size of the hippo they would not be able to sink so quickly.
Hey Cheryl!
What I also find fascinating is the fact that hippos share a common ancestor with dolphins and whales! No wonder they make those “clicky” sounds!
You bet they're quick! Hippos can reach speeds of up to 30 mph (48 kph) on land, and can even run as fast as a man can walk while under water. Bring it on Mr. Usain Bolt, you still have a bit of workout to do!
NB: Just to give you an idea, Usain Bolt ONLY runs at 37.57 kph. Easy peezy, run this in my sleep!