Free parking at Noiraigue station.
(S/E) Look out for the signs and head towards the Gorges de l'Areuse via Rue des Tilleuls; at the end of the street, turn right towards the railway tracks.
(1) Do not cross the tracks; instead, turn left and head towards “Saut de Brot” along a lovely path. Follow the railway line.
(2) Cross the tracks and take the path on your left to reach the gorges. Continuing to follow the railway line, cross a footbridge and arrive at Saut de Brot.
(3) Continue along the path to the hamlet of Champ-du-Moulin-Dessous.
(4) Take the path on the left, continue straight on, staying below the railway line, and ignore the steps on the left that lead up to the station. Continue straight on until you reach the bend.
(5) Look out for a narrow path on your right that leads uphill. Magnificent panoramic views and a view of Lake Neuchâtel. Continue to the refuge, ideal for a coffee break and a magnificent view of Lake Neuchâtel.
(6) Enter the Creux du Van Nature Reserve and continue straight on along the path.
(7) Turn off onto the path on the right and head to a picnic area, where a hut and several tables are available.
(8) Look for a path leading down to the right to reach the second part of the gorges. Be careful, you will need to cross the railway line!!
(9) Ignore the two paths on the right and head towards Pont des Clées.
(10) At the fork, continue towards Pont des Clées on the right. Go down the steps and reach the gorges via some steps (magical). Cross the bridge.
(11) Take the path on the right that goes uphill, towards Pont de Vert. A little further on, ignore the path going uphill. Keep going straight on; stairs, a narrow passage and a bridge lie ahead. Magnificent.
(12) Climb up to the Abri de la Baume du Four (there and back), then cross the Pont de Vert, still following the magnificent path, towards Noiraigue
(13) Please note: take the bridge, cross the Areuse and continue along the other bank to the next bridge.
(14) Cross the Pont de la Verrière and take the path on the right to the Verrière waterfalls.
(15) Cross the bridge on the right-hand side, then, at the end, turn left towards Noiraigue. There are a series of waterfalls, steps and a small tunnel along the route. You will come to some steps.
(16) At the top of the stairs, take the path leading down towards Treymont until you reach another bridge.
(17) Cross the bridge and, on your right, look out for a path leading down. Continue along this lovely path, following the Areuse, until you reach Champ-du-Moulin, where you can stop for a break at the Restaurant de la Truite.
(18) Look out for the building on your left; go round it and head right onto a small road.
(19) Turn onto the path leading uphill, Chemin des Rochettes, on your left. Ignore all other paths. Stay on the forest track.
(20) Look out for a path on your right and take it to go into the woods for a bit. Don’t panic if you miss it; the forest road leads to the same place.
(21) Turn right onto Chemin de la Ferme Robert and continue to the road.
(22) Follow the road for a few metres to the left (still heading towards Ferme Robert). Look out for a staircase on the left and take it. You’ll rejoin the road, then quickly leave it via the path on the left. After a few metres, cross the road again (be careful) to reach a car park.
(23) Head towards Noiraigue. Cross the car park on your right to join the Chemin des Chômeurs, keeping to the right. You will be in the forest.
(24) Stay on the main path and ignore the others. The markings on the trees will guide you.
(25) Keep heading towards Noiraigue on your right, along lovely paths, and start a steep descent towards the end. Take care. Continue until you reach a road.
(26) Head down the road on your left towards Noiraigue and pass the quirky "Luge Rouge" second-hand shop!
(27) Cross a bridge, continue along the road towards the station and you’ll reach the junction from the outward journey.
(1) Follow the route back in the opposite direction to the car park at the station (S/E).

As I was already more than 25 km into the single track, I turned back (I've already been up there, so there was no point in going back!).

. Done in 6h20