The Grumeti River is a river in Mara Region, Tanzania, situated almost entirely within the western corridor of Serengeti National Park. It flows westward and mouths into the Speke Gulf of Lake Victoria.
It is a major river crossing for the Serengeti great migration. During May to August, thousands of wildebeest and other animals cross the crocodile-infested waters. It is famed for this sight alongside Mara River.