Lac de Serre-Ponçon, Artificial lake in Hautes-Alpes and Alpes-de-Haute-Provence, France.

Lac de Serre-Ponçon is an artificial lake nestled between mountains in the Hautes-Alpes and Alpes-de-Haute-Provence departments, formed by damming the Durance and Ubaye rivers. The water surface covers approximately 28 square kilometers and forms one of the largest reservoirs in Europe.

Construction of the dam began in 1955 following devastating floods in 1843 and 1856 and required relocating several villages before the project was completed in 1961. The flooding of the valley submerged roads and farmland beneath the water and created a new landscape among the Alps.

The Chapelle Saint-Michel, first built on a hill in the 12th century, was destroyed by the army of Victor Amadeus II, Duke of Savoy, in 1692 and rebuilt soon after. It was condemned during the dam's construction but survived, its hill becoming an island in the lake. The island can be reached on foot in winter and early spring, when the reservoir is emptier.

The lake's level drops by up to 10 to 12 metres, so the shoreline shifts through the year; nine supervised public beaches carry the Pavillon bleu label. Around 1,100 moorings are spread across the ports along 91 km of shore, and three pontoon fuel stations stay usable down to low water. The Chapelle Saint-Michel island can be reached on foot in winter and early spring.

The dam structure reaches 123 meters (404 feet) in height and supplies water to a network of 15 additional hydroelectric plants along the Durance and Verdon rivers. When water levels drop, foundations of submerged buildings from the former villages sometimes emerge from the depths.