Go to the Merlins car park, taking the Route des Merlins from Susville (please note: Google Maps is not very familiar with the area and may try to take you up from Le Villaret, which is not possible by car). There is a large car park at Les Merlins; park on thefirst level, below thesecond.
(S/E) At the foot of the car park, on the left as you arrive, a sign points towards La Mure, on a good path that is almost flat, heading south-west.
(1) At the Champ Morand sign, go up to the right. Keep heading southwest until you reach a fork in the road, just before the power line.
(2) At the Combe Prunières sign, climb up to the right, under the power line, towards Le Sénépy, and continue towards Le Sénépy.
(3) At the crossroads: Écurie Bernard, continue straight ahead towards Sénépy and join the ridge of Serre de Chat Pendu.
(4) Turn right and head towards the Col du Sénépy.
(5) (For a return trip to the summit of Sénépy, take the winding path on the left).
Climb to the right, towards the ridge, leaving some hillocks on your left, then on your right. The general direction, north-east north, remains the same until you reach a flat area, clearly marked by herds.
(6) At the Aup sign, continue in the same direction, towards the copse of trees, to join a path that descends in the same direction, then gradually turns to the right to go around the hillock of Pierre Plantée (on the right). Note (thanks to Bapmab): at the grove, do not turn right onto the cattle tracks that lead to the start of a dead-end forest track, but continue in the same direction until you cross the indicated path which leads, at the entrance to the forest, to a turnstile with signs for Les Treize Bises.
(7) Continue to the right, due east, almost horizontally, to continue around the Pierre Plantée. Then enter the forest and head for Les Treize Bises and its cabin.
(8) With your back to the hut, descend south-east into the hollow of the valley. Go through a gate and turn right, heading due south, onto the main path signposted towards Les Merlins and the car park (S/E).
