The “Étang de la Gruère” is a dammed, but natural moor lake situated in a hollow on the highland plateau of the Franches-Montagnes in the canton of Jura.Together with the forested area around the lake itself, the nature reserve covers an area of 1km2.

It lies at an elevation of 998 metres a.s.l. on the municipality land of Saignelégier, approximately half way between Saignelégier and Tramelan. The lake is 600m long, 60m wide at its narrowest point and around 5m deep. Taken together with the forested area around the actual lake and two further small moor ponds to its north east, the Étang de la Gruère nature sanctuary comprises an area of approximately 1km2.

A path for hikers has been designed here that combines all the characteristic elements of the Franches-Montagnes high plateau. If you want to enjoy the scenery to the full all you have to do is to follow the signs and focus on the natural beauty around you as you walk. The trails are well developed with walkways and bridges. It is recommended to stay on the marked trails to avoid trampling the surrounding nature.