The Bassin des Esserts is a man-made water reservoir built in 1971 to hold the water coming from Val Ferret. This water is then used for the hydro power generation.  Technically, this is not a mountain lake and naturally it is not as beautiful as the natural lakes that will find all around Chamonix. It is very spectacular though and has great views and beautiful pastures all around the reservoir. The reservoir is absolutely massive can hold up to 220,000 cubic meters of water or the equivalent of 60 olympic sized swimming pools.

The Basin des Esserts lies in Switzerland right across the border near the Tete de Balme lift station. The easiest access is by taking the trail up from Vallorcine towards the spectacular Les Saix Blancs viewing point and from there continue onward towards the Tete de Balme chair lift. You can cross the border there and then its only a few hundred meters before you reach the reservoir.