I've always found Hippopotamus to be surprisingly intimidating. They're large swimming tanks with teeth. 
I think they look cute. They are mostly herbivorous semiaquatic mammals native to sub-Saharan Africa.
I might disagree with cute. Don't they like have loose stool and fling it everywhere with there tails to mark their territory? 
I've never seen them do that but it sounds wild. Their name comes from ancient Greek for "river horse".
I can believe that. I also heard they could snap alligators in half with their jaws.
They do have very powerful mandibles. Their closest living relatives are whales & dolphins.
Wow I don't think I knew that. I read that they also don't really swim and that the more of run along the bottom of the river. Is that true?
short distances.
The common hippopotamus inhabits rivers, lakes and mangrove swamps, where territorial bulls preside over a stretch of river and groups of five to thirty females and young. During the day, they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grasses. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land. The hippopotamus is among the most dangerous animals in the world
Hippopotamus
The common hippopotamus ("Hippopotamus amphibius"), or hippo, is a large, mostly herbivorous, semiaquatic mammal and ungulate native to sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus ("Choeropsis liberiensis" or "Hexaprotodon liberiensis"). The name comes from the ancient Greek for "river horse" (). After the elephant and rhinoceros, the common hippopotamus is the third-largest type of land mammal and the heaviest