A river is a natural channel where water flows from mountains or high ground to a sea or lake. Rivers are home to many different animals, including otters, kingfishers, Nile crocodiles, common frogs, red-bellied piranhas, and dragonflies. Rivers are also very useful to people, as we use them for drinking water, farming, industry, power, recreation, and transportation. Over thousands of years, rivers shape the surrounding landscape by cutting valleys and forming waterfalls as they flow, such as the Colorado River which created the Grand Canyon. Some record-breaking rivers include the Severn River in the UK at 220 miles long, the Nile River in Africa as the world's longest at