Reschensee (German: [ˈʁɛʃn̩ˌzeː] ; Austrian German pronunciation: [ˈrɛʃn̩ˌseˑ]; Italian: Lago di Resia [ˈlaːɡo di ˈrɛːzja]) or Lake Reschen is an artificial lake in the western portion of South Tyrol, Italy, approximately 2 km (1 mi) south of the Reschen Pass, which forms the border with Austria, and 3 km (2 mi) east of the mountain ridge forming the border with Switzerland. With its capacity of 120 million cubic metres (97,000 ac·ft) it is the largest lake in the province. Its surface area of 6.6 km² (2.5 sq mi) makes it also the largest lake above 1,000 m (3,300 ft) in the Alps. It is fed by the Adige, Rojenbach and Karlinbach and drained by the Adige.

The lake is famous for the steeple of a submerged 14th-century church; when the water freezes, this can be reached on foot. A legend says that during winter one can still hear church bells ring. In reality the bells were removed from the tower on July 18, 1950, a week before the demolition of the church nave and the creation of the lake.