Drive through Puy-Saint-Vincent, head towards the hamlets of Prey d’Aval and Prey d’Amont, and park at the end of the tarmac road.
(S/E) Take the wide track that climbs and makes large circular loops. After about 1 km, you’ll reach the plateau and the Col de la Pousterle car park. Take a moment to turn round and admire the view.
(1) Continue along this wide track, which soon veers off to the left. Climb steeply through the trees to reach a junction with a footpath.
(2) Turn right, following the signposts at each junction, and head up towards the lake. Following these signposts will keep you on the right track. The lake is signposted as 20 minutes away. Continue straight on until you come to another path crossing the one marked “par les peatlands” (signpost).
(3) Continue straight on; the path climbs slightly then descends. You will reach a path coming from your left with a very steep gradient. Take this path on the right, which climbs a little further, and you will reach the lake in 5 minutes.
(4) Return via the same route, but if you have the map, you’ll see there are several alternative routes available to get back to the car park (S/E).