Depart from the car park near the Markstein farm at the intersection of the D131 and D430 roads.
(S/E) Cross the D430 (heading north-west) to find the Blue Triangle signposted trail.
(1) After 330 m, at an intersection (tree with sign), turn right onto the Triangle Bleu trail, which will take you downhill to Lac de la Lauch. Please note: at 1.1 km, you will need to cross the D430 and go over the safety barrier to rejoin the trail.
(2) Turn right and follow the lake on your left to reach the dam.
(3) From the dam where the Rivière de la Lauch begins, continue to the D430, which you will take to the right for about 50 m to find the path on the left marked with a yellow rectangle. Be careful as the trail is not always well marked. Start the fairly steep climb through the forest and, when you reach a clearing, take the trail through the meadows to reach the Col d'Oberlauchen.
(4) Take the path marked with a blue disc on the left into the forest. Follow this flat, wide, shaded path until you reach the junction with the D27.
(5) Cross the D27 and take the path opposite heading north-west through the meadows. Keep heading through the meadows until you reach a sandy road and the Salzbach farmhouse inn.
(6) Pick up the path to the south marked with a red-white-red rectangle to reach the Fecht (nearby spring) and then the Col d'Hahnenbrunnen. At one point, the end of the path crosses a wider path; turn left for about 50 m to reach the intersection with the D430.
(8) After 50 m on the D430, turn left onto the path marked with a red rectangle (GR®5). Follow the ridge line southwards. At one point, you will cross the D430 again.
(9) Cross the D430 to pick up a path opposite heading south-west, which climbs towards the summit of Trehkopf. Do not take the red-white-red signposted road, which is dusty and congested with cars on Saturdays.
(10) At the summit of Trehkopf, there is a paragliding school and a beautiful view of the surrounding peaks. Retrace your steps along the same double path; a fence separates them. Take the right-hand path to turn east onto a path that descends (no markings).
(11) At the bottom, turn right, leaving the Jungfrauenkopf summit (ski lift) on your left. Follow this descending path, which passes through the edge of the woods, to finally reach the Markstein bar.
Return to the car park via the road on the right (S/E).
To get back into shape after lockdown, we completed two-thirds of this hike, starting from Dauvillers and beginning the ascent at the blue crosses above the waterfalls. The advantage of this route is that you can adapt it to your level, first at the lake and then when you reach Markstein. There is a beautiful variety of views, alternating between shade and open landscapes. The view of the Grand Ballon is superb when you reach the Oberlauchen pass.