Park your car at the Col d'Oderen car park.
(S/E) From the car park, take the Blue Rectangle trail (GR®531) on the other side of the road, heading towards Grand Ventron and Felsach. Follow it until you come to a junction further up, near a car park, where the small road leads to the Felsach farmhouse inn (or Felzach).
(1) Leave the GR® and follow the road to the right downhill to the farm.
(2) Pass the farm, continuing downhill, on the Blue Triangle-marked path which heads eastwards then curves to the right to go round the Felsakopf before heading east again, south of the summit, towards Frenz.
(3) Continue the descent straight ahead through the forest and then across the pastures until you reach a crossroads.
(4) Turn left towards the houses in the hamlet of Frenz until the path joins a wide track. Follow this to the right until you reach the road.
(5) Continue straight ahead on the road leading to a car park, cross it and follow the path down into the forest. After about 500 m, leave the path to the left onto a trail before crossing the Col d’Oderen road.
(6) Cross the road and continue straight ahead along the Blue Cross marked path, which joins the Saint-Nicolas stream and the Green Disc marked path.
(7) Follow the Green Disc path to the right, upstream, to the road and walk alongside it on the left for a few dozen metres before reaching the start, on the left, of a footpath (Green Disc).
(8) Head left uphill towards the Col d'Oderen until you reach the junction with the GR®531 (Blue Rectangle).
(9) Follow this to the right to the Col d'Oderen and the car park (S/E).