by the end of the day, when the sun is not too hot, the hippos get out of the water to eat some grass; this is the most dangerous period where you must say far away. every year when on a safari in Africa I ask the other people what animals they mostly fear and the answer is always: lions! What a mistake! hippos kill ten fold more people than lions, including tourists; they can get out of the water and run up to 30 km/h, faster than most humans! The hippopotamus is the world's deadliest large land mammal, killing an estimated 500 people per year in Africa according to the BBC.. Hippos are aggressive creatures, and they have very sharp teeth. Small boats can be capsized by hippos and passengers can be injured or killed by the animals or drown. In one case in Niger, a boat was capsized by a hippo and 13 people were killed Hippos are herbivorous, they don't eat humans, just cut them in pieces...