Do u know that the hippopotamus can stay under water for up to 2 minutes ? Yeah, its a real fact that a Hippo can calves nurse under water & automatically resurfacing to breathe.Because Their heart rate slows down. At the age of two months the hippo’s can staying under for 35 seconds. But the hippos cannot swim. They can see, hear & breath easily when they floating in the water.The hippos normally come up for air every 6 or 7 minutes, but they can stay under for about 30 minutes.