Engstlensee is a natural lake used as a reservoir in the municipality of Innertkirchen, Bernese Oberland, Switzerland. It is located near Joch Pass at an elevation of 1850 m. It can be reached by gondola and by foot from Titlis. The reservoir has a volume of 10.7 million m³ whereof 2 million m³ are used for electricity production. The lake's surface area is 44 ha (110 acres). The water of the Engstlensee passes through a tunnel in the neighbouring Gadmental valley before being used in the Fuhren, Hopflauenen and Innertkirchen power stations.