The country's main lakes are Lake Maracaibo -the largest in South America- open to the sea through the natural channel, but with fresh water, and Lake Valencia with its endorheic system. Other noteworthy bodies of water are the Guri reservoir, the Altagracia lagoon, the Camatagua reservoir and the Mucubají lagoon in the Andes. Navigation in Lake Maracaibo through the natural channel is useful for the mobilization of oil resources.