Start at Les Haizettes, at the crossroads with a wayside shrine and a bus stop. There are several parking options:
- Along the wide forest track heading west (taking care not to block the forest gates).
- In a small car park opposite No. 39 Route des Haizettes (the road that branches off to the left when facing the oratory).
- In another small car park further along the same road (at the name "Les Haizettes" on the 1:25,000 map). Take the road just behind the car park and follow it to the left (south).
(S/E) Opposite the oratory, turn right and take a wide forest track. Turn immediately left, go through a forest gate and take the wide grassy track running south-south-east parallel to Route des Haizettes. This track approaches the road (small car park mentioned above) and then turns right. Go through a forest gate and continue straight ahead on the D112 road. After about 150 metres, before the road descends, turn left onto Route les Haysettes au Parc d'en Haut (sign; note the difference in spelling from Haizettes). Go through another forest gate and follow a small paved road closed to motor vehicles heading south.
(1) At the crossroads (signpost), take the first path on the left (north-east). Be careful, this path is not very well marked; it starts at the foot (left side) of a tree with two thin twin trunks. Follow this grassy path to the corner of a fence at the foot of which you will find the first signpost.
(2) Continue along the path that branches off from the fence and turn right (east-southeast, azimuth 120 to be precise). Immediately ignore a path on the left (northeast), pass at the foot of a group of three birch trees on the right and continue east-southeast on the grassy path. After a wet section, you will come to a wider path. Keep heading east-southeast, crossing several small drainage ditches and a few forest tracks.
(3) At the T-junction at the edge of forest plots nos. 17 and 20, turn left onto a wide grassy path. Follow this path between two beautiful forests. Shortly before a wooden gate, ignore a vague path on the right and continue to the gate marking the boundary between the Rambouillet State Forest and the Domaine de la Mornaie (private property).
(4) Turn right and follow the fence on your left.
N.B. There are actually two parallel paths... It is recommended to follow the one closest to the fence, even if in places it is poorly marked and resembles a ditch: on the one hand, this is where the boundary markers are located and, on the other hand, the furthest path disappears into the vegetation beyond forest plot no. 12.
So keep heading north-east, ignoring the paths on the right, as the barrier is a good landmark that you should keep in sight. At plot no. 12, the wooden barrier gives way to a barbed wire fence. At the corner of this fence (boundary stone), leave it on your left and continue for about 50 metres, following vague tracks. Turn right, cross a "plank" bordered by small ditches and come out onto a grassy path.
(5) Follow this path on the left (north): this is the Route du Grand Veneur, which leads to the oak tree of the same name. Go through a forest gate and continue straight ahead on a wider path between two fences, first through the forest and then lined with a row of trees and between meadows.
(6) At the end of this path, follow the D112 road to the left. Just before entering the forest again, leave the road and turn right onto a path that starts between two fences (sign saying "Décharge interdite" [No dumping]). Go downhill, curving to the right. At the bottom of the descent, turn left onto a grassy path and follow a meadow on your right. Then climb between the hedge or fence on your left and the fields on your right, ignoring a path coming from the right.
(7) At the next intersection, turn left and continue for about 400 metres to enjoy a view of the Château de la Mormaire and its grounds. Retrace your steps.
(7) Turn left (west) onto the main road. Ignore a path leading down to the right towards a wood and continue straight ahead towards some houses. The road gives way to a tarmac lane; follow this to the crossroads with the oratory (S/E).