Monkey River is a coastal watercourse in southern Belize that rises in the Maya Mountains and discharges to the Caribbean Sea near Monkey River Town. One of Belize's major rivers, Monkey River has northern headwaters which originate in the Cockscomb Basin Wildlife Sanctuary, where the Swasey Branch drains the East Basin of that wildlife sanctuary. Further south, the Bladen Branch watercourse drains the eastern slopes of the Maya Mountains including the ancient Mayan settlement areas of Lubaantun and Nim Li Punit. These two watercourses join to form the Monkey River approximately 16 kilometres upstream from the mouth of the Monkey River. The Monkey River is readily navigated throughout the year using small boats, but navigation above the major confluence (of Bladen and Swasey Branches) becomes more difficult due to lack of depth when the dry season starts about February.