Laguna del Negro Francisco is a lake in the Atacama Region of Chile and the southernmost closed lake in the country. It is situated 200 kilometres (120 mi) northeast of the city of Copiapó. The lake is about 10 kilometres (6.2 mi) long and 4 kilometres (2.5 mi) wide with a surface area of about 20.7 square kilometres (8.0 sq mi) and a depth of about 1 metre (3 ft 3 in). A peninsula, probably formed by a moraine and subsequently modified by wind-driven accumulation of sand, separates the lake into a north-northwesterly and a south-southeasterly half with different colour and water composition.