Belonging to the cavy family (Caviidae), their closest relatives are actually guinea pigs and rock cavies. They’re essentially the rodent version of the hippopotamus—gnawing their food while swimming in the South American swamps. They eat their own poop to extract maximum nutrition from their food—much like rabbits. 

Capybaras can dive and stay underwater for up to 5 minutes at a time, often falling asleep in the water while keeping their nose at the edge of the banks. Napping along rivers, mangroves and marshes helps them to stay cool.