Boucle d'Oyonnax à la Prairie d'Échallon

Author's update on 14/10/2025:

• adjustment of the route shortly before point (3),
• renaming of the point (3) to Ravin du Fouget (corresponding to the signpost)

Update by the author on 16/10/2025: error in the correction of the point name (3): it is indeed Les Grands Prés (Ravin du Fouget is located higher up).

The starting point is Place des Déportés 1944 in Oyonnax, in front of the Lycée Paul Painlevé. Parking spaces are available.

(S/E) Head towards Rue Confas (north-east) and, after crossing the bridge over the Sarsouille, turn right onto Chemin du Petit Moulin.

(1) At the end of Chemin du Petit Moulin, turn right towards the Sarsouille river and take the path following the course of the river on its left bank. At the^first fork, continue straight ahead, still following the course of the river. Shortly after a metal footbridge, cross the river via large stones secured by cables. (There are seven river crossings in total).
Continue along the path for a short while alongside the river.

(2) At the Route Forestière de la Brétouze, continue straight ahead to the left of the bridge (follow route no. 6 Prairie d'Echallon).
Not far away, turn left onto an uphill path. Join another path on the right. After a short while, you will come to a carriage road.

(3) Take the path on the left, then almost immediately take a path on the right.
(4) At the RD13 road, take the path opposite uphill (towards Grotte de Lordon). The slope is a little steep until you reach a fork.

(5) Turn left towards Grotte de Lordon, which is not far away. It is quite pretty in its own way: be careful as the ground can be slippery.
Retrace your steps to the fork, then turn left (towards Prairie d'Échallon).
Further up, you will reach another path. Turn right (yellow markings + Trail No. 10). After a gentle slope, the path becomes significantly steeper as it descends to a fork.
Take the path on the left uphill: this path is quite steep (always follow the two markings). Further up at a fork, turn right and continue uphill.
The slope then levels out. At a fork, continue straight ahead (towards Prairie d'Échallon).
Not far away, at another fork, turn right (signpost = Sentiers) and continue to another fork.

(6) Source du Fouget (as indicated on the IGN map). At the crossroads, continue straight ahead towards Prairie d'Échallon (yellow markings).

(7) At the forest road, continue straight ahead (yellow markings). Shortly afterwards, you will reach a large deforested area known as Prairie d'Échallon.

(8) Pyramid-shaped structure: this is the Monument du Maquis. Turn left onto the path crossing the northern part of the meadow. In a forest environment, you will then reach a forest road after passing under a power line.
A sign indicates Les Mousse; turn left onto the road and continue for about 100 metres.

(9) Then turn right towards Sur les Mousses (yellow markings) and head towards the overhead high-voltage power line pylon.

(10) In a clear spot, enjoy the beautiful view (despite the high-voltage power line).
Retrace your steps and quickly take a path on the right. After a short, steep descent, turn right at the fork.

(11) Towards the end of the path, you can discover another viewpoint overlooking a cliff through a few trees (be careful!): this is the pretty lake of Sous les Mousses (not visible from the previous viewpoint).
Retrace your steps to the path leading to the^first viewpoint, then turn right to return to the forest road.

(9) Take this forest road on the right and continue for just over 1 kilometre.

(12) Just before the forest house, take a path on the right (marked by cairns and yellow markings). At a fork, take the right-hand path downhill.
The slope becomes steeper after a short section carved into the rock.

(13) Col (Roche Taillée) where you will see ruins on the left. Head right (follow the yellow markings) and when you reach a house (private forest property), Lac des Mousses will come into view.
Continue straight ahead until you reach a meadow to see the pretty Lac de Sous les Mousses.

(14) Please note that the surrounding area is private property and access is not permitted. A shame...
Then retrace your steps to Roche Taillée.

(13) Continue straight ahead, following the yellow markings. Further down, turn right at a fork (following the yellow markings) until you reach leat du Lac (Le Longviry).

(15) At La Boissière, follow the small road for about 500 metres until you reach a fork. Turn left, following the yellow markings. Along the way, you may catch glimpses of Lac de Viry on your right.
(16) At the pass, turn left onto the Route Forestière de la Chaux, which climbs for less than 700m.

(17) Turn right onto a road that climbs steeply at times (follow trail markers no. 10)

(18) At the fork, turn left towards Cul de Lary (in fact, the direction seems wrong as it is actually Mont de la Chaux). Along the way, it is possible to reach the summit (as indicated at one point on the left) but there is little of interest there.

(19) At the end of the path, you can access two viewpoints as indicated by the signs (and the trail markers). Then retrace your steps back to the fork.

(18) Turn left and head downhill. The path climbs slightly before reaching another fork.

(20) Take the path on the left, which climbs quite steeply (yellow markings + Trail No. 10). After passing Molard Rond, the path descends gently to a small viewpoint, then the slope becomes steeper. After a short while, you will come to a fork marked by a cairn. Turn left and continue for a few metres.

(21) Pointe de Biez is a beautiful viewpoint. Continue along the path on the left. Ignore the path on the right heading due north. The path you are following then descends steadily with slopes of varying steepness.

(22) Just before a clearly visible forest road, turn left onto a path (no markings); this path joins a road (RD13) further down, which you should cross. Follow the Forestière de la Brétouze road for less than 300 metres to find the start of a path on the right (blue and orange markings) leading downhill (be careful on wet ground).

Further down, rejoin the path you took on the way up, following the Sarsouille river and turning right as you descend.

(1) After passing Chemin du Petit Moulin, continue left to return to the starting car park (S/E).

Good hiking boots are recommended.
Walking poles are also recommended in wet terrain.

The starting point is here.

Nature has a hard time digesting your rubbish. Take it with you!

The visibility of the route shown is good:
- From (S/E) to (1) no markings,
- From (1) to (3): yellow markings,
- From (3) to (6): Trail No. 10 markings + yellow markings,
- From (6) to (10): irregular yellow markings,
- From (10) to (12): no markings until the second viewpoint over the lake and on the section of road leading to the forest house,
- From (12) to (13): yellow markings + cairns,
- From (13) to (16): yellow markings
- From (16) to (17): irregular yellow markings,
- From (17) to (18): trail markings no. 10,
- From (18) to (19): yellow markings,
- From (19) to (20): yellow markings,
- From (20) to (22): trail marker no. 10 + yellow marker,
- From (22) to (1): blue and orange markings to the Sarsouille river, then yellow markings,
- From (1) to (S/E): no markings.

It is possible to shorten the route:
- at (9) avoid the Belvédère viewpoint over Les Mousses (10) by staying on the road,
- at (13), avoid Lac Sous les Mousses by turning left at the fork

Access to the shore of Lac de Sous les Mousse is not permitted by the owner (there are several signs to this effect).

Access to Lac de Viry does not appear to be possible.

Maquis Monument: this monument is dedicated to the Resistance in the region and to the aid provided by the Allies by air between 1943 and 1944. Read more here and here

Lakes Viry and Sous les Mousses: read here