Hippopotamus is Greek for “river horse,” and the animal has been known since ancient times. Hippopotamuses are often seen basking on the banks or sleeping in the waters of rivers, lakes, and swamps next to grasslands. Accounts recording the number of human deaths per year by hippo attack range from about 500 to about 3,000. It is thought that hippo attacks on small boats are antipredator behavior, with the hippos mistaking them for crocodiles. As a result, hippos have long had a largely undeserved reputation as aggressive animals.

Source: Britannica