Hippos can be very dangerous. They are considered as one of the most dangerous animals in the world. In Africa, most human deaths by animals were caused by hippos. They are very mean if a person taunts them, they might attack the person. Even though they are really big, they can run at about 20 miles per hour. For an animal that size, that's pretty fast. They have 2 large tusks on the bottom of their mouth, which can be up to a foot tall! When you combine all of those things, you get one dangerous animal!