Lac de Divonne, Artificial lake in Divonne-les-Bains, Ain, France

Lac de Divonne is a man-made lake in Divonne-les-Bains covering about 45 hectares with water depths of roughly 3.5 meters. A promenade circles the shore for about 3.3 kilometers and connects to a supervised beach, picnic areas, and nearby facilities including a mini-golf course, nautical center for water sports, and a media library building.

Jean Debaud proposed giving Divonne a lake in 1945, and on 1 June 1946 he and geologist Paul Morel founded the Société d'étude du lac artificiel de Divonne with 14 members, including mayor Marcel Anthonioz. The site in the Grande et Petite Champagne marshes was fixed in 1958, chosen for its late-afternoon sun away from the Jura. Gravel sales to Swiss firms building the Geneva-Lausanne motorway helped fund the work; digging ran to 1964, and filling took thirteen days, ending 10 June 1964.

The lake became the centerpiece of community life in Divonne-les-Bains after it was created in the 1960s from marshland. Locals and visitors gather along the shores for recreation and picnics, making the water a social hub that shapes how people spend their free time.

The lake is open year-round with activities varying by season: summer offers swimming and water sports like sailing and kayaking, while spring and fall are better for walking and birdwatching along the shoreline. Picnic areas, sports facilities, and leisure parks are easily accessible from the promenade and welcoming to families and visitors of all ages.

The lake is fed by an underground water table beneath the former marshes, not by the Versoix. When digging began, water filled every hole, so in 1961 an electric pump was installed to work dry; the flow of 800 m3 per hour was enough to keep the level and renew the water.