A large inlet of the Caribbean Sea, lying in the Maracaibo Basin of northwestern Venezuela. It is the largest natural lake in South America, covering an area of about 5,150 square miles (13,300 square km), extending southward for 130 miles (210 km) from the Gulf of Venezuela, and reaching a width of 75 miles (121 km). Many rivers flow into Lake Maracaibo, the most important being the Catatumbo River, a transportation artery for products from the adjacent regions and from the Colombian-Venezuelan highlands.