Lago Rapel is an artificial reservoir in Chile's O'Higgins Region, roughly two hours south of Santiago.

Created between 1956 and 1968, it was built primarily to supply the Central Hidroeléctrica Rapel — which generates 350,000 kW — and to support agricultural irrigation in the region.

The reservoir holds approximately 695 million cubic meters of water and covers more than 8,000 hectares. Submerged beneath its surface are former towns, roads, and railway stations from the valley that was flooded during construction.

Over the decades, Lago Rapel has become a popular warm-season destination. Visitors come for a range of water sports including windsurf, waterskiing, wakeboarding, sailing, and fishing, as well as boat excursions.

The area around the lake supports numerous resorts, vacation homes, restaurants, and campgrounds.