A long walk in the Massif des Trois Pignons

Departure from the Canche aux Merciers car park, near the A6 motorway. Access from the D64 road connecting Arbonne-la-Forêt and Achères-la-Forêt.

(S/E) After the barrier, take the first path on the left. Then turn right onto Chemin de la Vallée d'Arbonne.

(1) At the next crossroads, continue straight ahead (our return route comes from the left). After about 500m, take a small, well-marked path on the left. After a steep climb, you will reach the Maison Poteau ridge (viewpoint).

(2) Turn right (do not follow the paths that go downhill). Head northwest and you will reach a large crossroads.

(3) Look for a post with a blue marker on the left (Denecourt-Collinet trail no. 16). Follow this marked trail southwards, which leads to a beautiful viewpoint after 300 metres.

(4) Leave the blue trail heading west and follow the red-marked 25 Bosses route to the right (south-west). Descend into a small valley and climb up opposite to the Pignon des Maquisards (monument with the Cross of Lorraine).

(5) Leave the red route, pass in front of the cross and take a well-marked path that follows the edge of the plateau heading west. The plateau is narrow at first, then widens slightly. Leave a path on the left and move away from the southern edge. The path winds through a very peaceful setting. After a short climb, you will reach Roche au Four.

(6) Take the red route again, on the left (south), and descend La Roche au Four. At the bottom, cross Chemin de la Vallée Close and climb up to Rocher des Souris. Pass Rocher Jean des Vignes (very beautiful views) then a third "gable".

(7) At the bottom of the descent, cross a path (the first since Chemin de la Vallée Close) and follow it to the left (leaving the Red route). At the next crossroads, follow Chemin du Mont Pivot to the right. Cross the Red trail and continue straight ahead.

(8) At the next crossroads, take a sharp left (south) onto Chemin de la Saussaye. Shortly before the barrier at the Roche aux Sabots car park, take the path on the left. Cross the wide Chemin de la Plaine Jean des Vignes and continue straight ahead. At the next crossroads, after 100 metres, rejoin the red route.

(9) Turn right onto the red route, climb (south) and then cross (north-east then south) La Roche aux Sabots. Climb another small hill and descend (wooden steps).

(10) At the bottom of this descent, leave the red route (which heads south-east) and turn left (north-east) onto Chemin des Sables du Cul de Chien. It crosses another path, then enters (and disappears...) into the sand. As the path disappears into the sand, look for the rock nicknamed Bilboquet, with its distinctive shape, in the middle of the large sandy basin. Walk along it on the left to reach a small, clearly visible sandy pass. On the other side, there is another sandy hollow. Head for the rocks in the middle of it. Continue straight ahead for about 10 metres, then look for a pair of V-shaped birch trees on the right: a "path" starts to the left of them and winds its way through the rocks, veering slightly to the right. Pass between the climbing rocks with blue markings. Ideally, you should leave rock no. 20 on your left and rocks nos. 14 and 15 on your right: you are now heading in the right direction... After about 100 metres, you will reach another sandy depression. Climb up to the right. Opposite, after about 100 metres (you will be more or less in the middle of this sandy area), a path begins on the left. Take it and you will quickly come out onto the Ancien Chemin de Melun.

(11) Cross this wide path and continue straight ahead. You will come out onto the Chemin de la Plaine de La Mée and follow it to the left. You are now at the foot of the Rocher du Général (very beautiful and uncrowded climbing routes). A little further on, cross the^GR®1and come out onto the Chemin de la Mée. Turn left. After about 300 metres, turn sharply right onto a path that turns sharply to the right. After 200 metres, you will rejoin the Red 25 Bumps route at the foot of Rocher de la Tortue.

(12) Follow the red route to the right and climb. Turn left and climb the Grande Montagne. Follow the red route until you come to a fork in the red route: a dotted line to the right, climbing a small rock to the left with a solid red line, for a rough route with small rock jumps. Choose either option (this is the "official" route marked here) and descend into a small valley where the two options meet.

(13) At this point, leave the red route (which goes back up opposite) and take a path on the left. This is the old^GR®1trail, and a nearby rock still bears an old marker. Follow this path east-southeast, which then turns right (south). At the crossroads, take the wide Chemin des Béorlots on the left and climb up to the plateau.

(14) At the fork, take the Chemin de la Platière on the left. Turn right at a right angle to the path and ignore the Chemin du Cerf on the right. At the T-junction, turn left onto the Chemin Vert. 200 metres further on, the Chemin Vert continues to the right, but continue straight ahead. After a descent, you will come out onto the Chemin de la Sambine.

(15) Turn left, the path descends towards the Vallée Chaude and leads to Chemin de Melun in Le Vaudoué. Then turn right and, shortly afterwards, enter the Vallée Chaude. Go up this valley to the east and then north-east. N.B. The path marked with dashes on the 1:25,000 map is not visible on the ground; follow the solid line further south.

(16) Shortly before the edge of the trees, follow a well-marked path on the left (yellow markings). Cross Mont Rouget (beautiful view of the Vallée Chaude) and descend on the other side. Turn right onto Chemin des Cavachelins, pass under the motorway bridge and continue straight ahead (the relief will quickly reduce the noise of traffic).

(17) Cross the D64 and continue straight ahead (Route de la Fontaine Marguerite). Immediately afterwards, take a path on the left which joins the Route du Moine further on. This then leads to the Route Descamps. Turn left and head for the Bois Rond car park.

(18) Cross the D68 again. Behind a beautiful oak tree, look for the path with the^GR®1sign. Follow the^GR® (red and white markings), climb along the motorway and turn right onto Chemin des Cassis. Pass under the motorway again and continue straight ahead until the next crossroads.

(19) Leave the^GR® straight ahead and turn left onto the old Tour du Massif de Fontainebleau trail (old green and white markings). At the bottom of the descent, do not continue straight ahead but first turn right then left to head west-southwest. At the next path (Chemin de Cavachelins), turn right and then immediately left. You will then very quickly come out onto the red trail.

(20) Turn right onto the red route (pine tree with the number 123 and a sign saying "Le Comptage"). After 400 metres, you will come to the most difficult part of the 25 bumps route, the descent (in this direction) from the plateau: avoid it by going to the right. At the bottom, follow the^GR®1to the right (red and white markings) and climb back up to the plateau. At the crossroads (elevation 118), leave the^GR® and take the Chemin des Gros Sablons on the left. After a pine tree with a sign indicating the name of the path, the path widens onto flat ground.

(21) On the left, you will see a well-marked path and on the right, a less visible path that leads into the undergrowth: take this path and follow it as best you can. After 200 metres, turn right onto Chemin des Cassis. After a crossroads where Chemin de la Maison Poteau branches off to the left, continue straight ahead (east). After a few metres, turn left onto a wide path (not shown on the map) between plots 111 and 112 (white marks on the trees). As you descend from the plateau, the path joins the dotted line shown on the map.

(1) At the next crossroads (taken on the way there), continue straight ahead. Then turn right to reach the car park (S/E).

There areseveral ways to shorten the hike:

• at the foot of Mon Pivot, follow the red route to reach La Roche aux Sabots
• after (16), before going under the bridge, turn left onto the Vallée Ronde path and return to the end of the route.

A 1:25,000 map or GPS track is essential. This hike requires a good sense of direction.

The actual elevation gain is greater than that calculated automatically (expect around double).