Hippopotamus

Hippopotamuses love water, which is why the Greeks named them the “river horse.” Hippos spend up to 16 hours a day submerged in rivers and lakes to keep their massive bodies cool under the hot African sun. Hippos are graceful in water, good swimmers, and can hold their breath underwater for up to five minutes. However, they are often large enough to simply walk or stand on the lake floor, or lie in the shallows. Their eyes and nostrils are located high on their heads, which allows them to see and breathe while mostly submerged.

Description
The Hippopotamus is an African mammal that lives partly in water and partly on land. Although strictly a plant eater, the Hippopotamus has massive jaws with a formidable tusks and an unpredictable temper. This creature is a good medium-cost attack unit due to its high health and ferocious bite. Due to its highly social nature, it also has herding ability, making it more effective when used in groups of 4 or more. Decent armor, along with the ability to be just as effective in the water as on land, make the Hippo a good mid-level offensive creature.