Which natural lake is Spain's largest?

Lake Sanabria is Spain’s largest natural lake.

Located in Zamora Province in northwestern Spain, Lake Sanabria covers about 368 hectares, or roughly 3.7 square kilometres. It is also the largest glacial lake in the Iberian Peninsula, a distinction created by the powerful ice sheets that shaped the surrounding mountains during the Pleistocene.

The lake occupies a basin carved by glaciers in the Tera valley. The Tera River is its principal watercourse, supplying and draining the lake, which reaches a maximum depth of about 51 metres. Its clear, relatively low-mineral water supports a distinctive aquatic environment, while surrounding wetlands include unusual sphagnum bogs.

Lake Sanabria became a protected natural area in 1946 and was designated a natural park in 1978. It is sometimes confused with Spain’s much larger reservoirs, such as Embalse de Alcántara, but those are artificial bodies of water. Sanabria also has a tragic modern history: the 1959 failure of the Vega de Tera dam caused a devastating flood at Ribadelago, with 144 people killed.