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Park below the Col du Coq on the road of the same name, in a car park along the D30E. Walk 100 metres down the road and you will find the marked start of the path leading up to the Dent de Crolles on your left.
Trou du Glaz:
(S/E) Take the winding path, initially through the forest and then quickly into the mountain pastures, marked in yellow, heading generally north towards the Col des Ayes.
(1) At Col des Ayes, turn right, heading due east, onto the steep, winding path marked in red and white (GR®®9) climbing towards Trou du Glaz and Dent de Crolles.
(2) At the junction marked by a signpost, turn left onto theGR®®9, which heads north-northeast towards Trou du Glaz. The path passes through a narrow corridor between two rock faces before reaching Trou du Glaz, the entrance to a vast network of underground galleries beneath Dent de Crolles.
Continue on theGR®®9trail, passing through several small rocky passages that are a little slippery but equipped with good cables. After the third cable passage, you will reach the junction marked by a cairn on the Sangle de la Barrère, which branches off to the right heading due south (see photo taken from the cliffs above ,Sangle Barrère).
Arche à l'Aiguille and Promontoire:
(3) Opposite the cairn, slightly below, a path leads northwards, marked with a red and white cross (to the left ofthe GR®®9as you climb). Take this path, which quickly becomes a narrow ledge bordering the void.
Caution: the trees bordering the path often hide the drop, but a misstep can be fatal.
Follow the path generally northwards and pass under a rocky overhang on the cliff. As you emerge from the overhang, look up regularly to spot the arch (it is easy to miss). It has a distinctive appearance, see photo (Arche à l'Aiguille Sud).
(4) Under the Arch at the Aiguille, climb a steep earthy slope to the right of the ledge (east), then take a foothold under the arch itself. Then cross the arch to the north and descend by sight down very steep grassy slopes on the ridge. This passage is dangerous, so proceed with caution despite the superb view (Arche à l'Aiguille Nord).
The ridge then continues north-east to the end of the Rochers de Bellefont and reaches less steep slopes dotted with mountain pines. After a right turn, climb these slopes southwards then south-westwards, proceeding on sight. If you feel a little disoriented, the easiest thing to do is to stay close to the top of the cliff that you previously walked along in the other direction at the bottom.
(5) This will take you to the promontory, which offers a beautiful view of the Roc d'Arguille, the plateau and the eastern cliff of the Dent de Crolles. Along the latter, you will see a strap (the Barrère strap), which you will use at the end of the hike.
Descend from the promontory via a cairned path that first heads east and then turns right towards the south to reach an altitude of 1,786 metres, where theGR®®9crosses numerous paths and there is a signpost.
Cheminée du Paradis:
(6) From this junction, take the path through some sharp limestone pavements that climbs south-south-west towards the summit of Dent de Crolles, paying close attention to the terrain on the left.
(7) At an altitude of around 1830m, a path branches off to the left (south-west) and climbs towards the ridge, skirting around the south of some very large sharp limestone pavement forming a slight depression. Follow this path or climb up the edge of the rocky basin to reach the ridge path which heads north-east along the eastern cliff of the Chartreuse.
Take this path to the left towards the northeast, always taking the paths closest to the cliff (take the highest path whenever possible).
This will first take you to the Thérèse cave, then through a pile of boulders marked by cairns, to Rocher Pointu and the pass (1,898 m) before the Cheminée du Paradis.
(8) Enter this chimney (after putting your walking sticks in your rucksack if necessary) using both sides of the chimney to progress, then turning to the left for the last few metres (8m in total).
Caution: at the top of the chimney, do not take the dangerous ledge that runs north, but climb up to the right (east) towards the cliff to reach the ridge. Old red markings indicate the way.
Continue along the ridge to the north, staying as close as possible to the east cliff to enjoy the view and stay on course. Pass the 1912m and 1938m peaks before arriving at the Pas de Rocheplane, marked by an old wooden sign.
(9) At Pas de Rocheplane, take the very steep path on the left which descends north-west towards theGR®®9. Reach theGR®®9after crossing a few small rocky outcrops.
Chaos de Bellefont:
Warning: the GPS track is inevitably inaccurate on this section of the route, so rely mainly on the red and orange markings.
At the intersection with theGR®®9, turn right to the north-east, following the almost horizontal path marked in red and white.
(10) As you pass a scree slope, note the red/orange markings on the rock and a descending path that branches off to the left in the opposite direction (south-west) before turning right due west.
Take this path, carefully following the numerous red/orange markings that mark the route, until you reach the Z-shaped crevasse that allows you to descend a rocky ridge.
The top of the Z-shaped crevasse is not obvious. Refer to the photo (Top of the Z-shaped crevasse) showing two large faults on either side of a rock behind a tree. Do not take either of the two faults, but instead climb onto the rock. Once on the rock, continue straight ahead (on the line equidistant from the two faults) to find a small step down, then descend to the left into a new fault marked with red/orange signs.
(11) Once past the Z-shaped crevasse, the route continues westwards along a high cliff on your left, then joins a path at the foot of the cliffs which heads left, generally south-west. Follow this path until it intersects with a steep, winding path, the Prayet path.
(12) Take this path uphill towards the east. After numerous switchbacks, it joins theGR®®9.
(13) At the intersection with theGR®®9, turn right onto it, heading back south then south-west to the crossroads at an altitude of 1786m, which you already passed on the way there.
(6) Turn right onto theGR®®9heading west to reach the intersection with the Barrère ridge.
Barrère ridge and eastern ridge:
(3) At the intersection of the ridges and theGR®®9, turn left heading due south to climb up along the western cliff of the Dent de Crolles. The ridge is spacious, but the view of the void can be impressive. Several climbing routes start from this ridge, sometimes with fixed ropes.
After a sustained climb, the belt slants south-east, descending towards the Pas de l'Œille.
(14) At Pas de l'Œille, marked by a rocky peak, do not follow the yellow marked trail that climbs directly to the Dent, but continue southwards towards the south pillar of the Dent, below the small summit cliff, on a relatively well-marked path. Be careful, as several paths lead to the south pillar at different altitudes. It is essential to follow the one that passes by the Aiguille du Pas de l'Œille.
(15) This will take you to the start of the eastern strap, sometimes marked by a small cairn. Immediately after the corner of the cliff, the path turns north-east and leads to a passage where the ground has collapsed. Before setting off, it is essential to put on your helmet and put your poles in your rucksack.
Caution: The slightest misstep or fall is fatal on this ledge carved into the cliff, see the photo of the eastern ledge.
A rope followed by a well-anchored cable allows you to pass the exposed section. Shortly afterwards, a small platform sheltered under an overhang allows you to pick up your walking poles again. However, do not remove your helmet.
Continue along the ledge (north-east) admiring the view (E) but taking care not to slip. The ledge eventually climbs up slightly less steep slopes towards a ridge in the summit cliff.
Dent de Crolles:
(16) At the ridge, turn back towards the south-west and follow the summit ridge to Dent de Crolles (metal cross and bivouac shelter) then the southern tip of the Dent, which is less frequented but more spectacular.
After taking the usual photos, head northwest for 200 metres along the western ridge of the Dent to find the yellow-marked trail that descends via the Pas de l'Œille.
(14) Turn left and join theGR®®9.
(2) Follow the outward route to reach the Col des Ayes.
(1) Then return to the car park (S/E) following this recommendation: carefully descend from the Col des Ayes without cutting the bends, as the area is undergoing vegetation restoration, to reach the road and the car park.
Tourism professional
Very difficult 
Visorando member
Moderate 
Difficult 
