Hippos spend most of the day in water because their mass to volume ratio is so high that if they were to stay in the scorching sun for too long, they would die of dehydration.
Rising to breathe and then submerging itself in water again, is an involuntary process for a hippo; they an even do this in their sleep.
A grown up hippo can stay under water for up to 5 minutes.
A hippo can consume up to 40 kilometers of grass and they are known to wander as far as 10 kilometers in the evenings, in search of food.
Hippos secrete a red oily fluid from its pores to protect it from sun burns.