The Ester Mountains (German: Estergebirge) are a small mountain range in Bavaria. They are classified either as part of Bavarian Prealps or the larger chain of Northern Limestone Alps. The range stretches for about 15 kilometres. From the west it is bordered by the valley of the river Loisach and from the east by Walchensee lake and the valley of the river Isar. With its highest peak being Krottenkopf (2,086 m), the highest part of the range just exceeds 2,000 m. The range is of composed of limestone. The treeline is around 1,700 m.