The Essential Role of Water in Hippopotamus Survival Hippopotamuses are semi-aquatic mammals that rely heavily on water for their survival. They inhabit rivers, lakes, and swamps, where they spend a significant portion of their day submerged to keep their bodies cool and to protect their sensitive skin from sunburn. Water is crucial for their thermoregulation, as they cannot sweat. Bonobos African Safari Holidays G Adventures Lonely Planet TED The National Desk - TND Team USA Intrepid Travel 5-M