Departure from the Feuillardière car park, along the D409 between Milly-la-Forêt and Arbonne-la-Forêt.
The route is not marked, but there are occasional signs for the "Promenade de Sucremont" and small yellow signs showing the silhouettes of two hikers, one of whom is a child.
(S/E) At the car park entrance, with your back to the road, head south along Chemin de la Borne à l'Enfant (signposted "Promenade de Sucremont"). Continue straight ahead, ignoring the paths branching off to the sides.
N.B. Contrary to the directions on the 1:25,000 map, Chemin de la Sapinière is not the first path on the right but the second.
At the Carrefour de la Feuillardière (rocks on the slope opposite), turn right onto Chemin de Trappe Charrette. At the next fork, turn left and you will arrive at the foot of the Aqueduc de la Vanne et du Loing.
(1) Pass under the aqueduct through an archway built for this purpose. Turn right immediately and walk along the aqueduct on your right. At the end, go around the masonry structure on the left, going uphill. At the top, turn right onto the wide grassy bench of the aqueduct, which has now gone underground.
(2) At a fork, leave the bench and go left towards a sign for "Sucremont". Follow a path that enters the undergrowth and then climbs up through the heather. Climb a flight of wooden steps on the right, continue climbing and then climb a second flight of steps. At the top, turn left (sign on a small wooden barrier). Heading generally west, wind your way through the undergrowth on a good, fairly flat path.
(3) At a small clearing (view of the Coquibus massif on the left), turn right onto Chemin de Sucremont (sign on a tree). Head north-northeast on a wider path than before and ignore a vague path on the left (forest plot no. 92) and a grassy lane on the right. Turn right with the path and descend slightly, heading east.
(4) At the bottom of the descent, find the grassy embankment of the aqueduct and follow it to the right. At a right-hand bend, leave the embankment and take a path downhill to the left. At a fork immediately ahead, follow Chemin de la Sapinière to the right (the purple line on the map is inaccurate here). Immediately after, at a second fork, turn left and then, immediately after, at the third fork, turn right. Walk due east and, shortly after a sign on the left-hand side, follow a path on the left that descends into a sort of hollow. Climb back up opposite and return to the car park (S/E).