The Rosny Forest

A mainly forest route west of Mantes-la-Jolie. Along the way, there are several remarkable trees and a few limestone grasslands, which constitute a unique natural heritage as well as a great opportunity to take a break.

Technical sheet

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  • Walking
    Activity: Walking
  • ↔
    Distance: 14.80 km
  • ◔
    Average duration: 4h 55 
  • ▲
    Difficulty: Moderate

  • ⚐
    Back to start: Yes
  • ↗
    Vertical gain: + 230 m
  • ↘
    Vertical drop: - 228 m

  • ▲
    Highest point: 151 m
  • ▼
    Lowest point: 44 m

Photos

Description of the walk

Departure from the village of Apremont, a few kilometres south of Rosny-sur-Seine. Park in the small car park at the end of Rue du Manoir (half a dozen spaces). If there are no spaces available, park in the adjacent streets, particularly Rue du Beauvoyer, heading towards the D114.

Red and white markings (sparingly)

(S/E) Facing the manor gate (no. 6), turn left, leave the wash house on your left and turn right at the corner of the wall. Climb up through the undergrowth on a grassy path that becomes hollow and ignore the vague paths branching off to the sides. Continue on flat ground at the edge of the woods on your right. Come out onto the D114, follow it to the left uphill and enter La Belle Côte.

Red and white + orange markings (sparingly used)

(1) At the corner of No. 22, turn right onto Chemin du Clos Nonand, lined with poplar trees. Facing a gate, turn left onto a path and walk along the right-hand side of a large brick building. Continue through the undergrowth, passing a pond on your left and then another on your right, until you reach a crossroads (car park on the left).

(2) Cross the tarmac road and, on the other side, take the path furthest to the right (do not follow the Sentier du Poirier Godard, signposted). Descend slightly and you will arrive at the Mare du Désert (on your right).

(3) Ignore the path coming from the left and continue straight ahead. Stay west-southwest on the main path, which is occasionally flanked by a parallel path on the right-hand side. Pass a forest barrier on the right-hand side, ignore a path branching off to the right and, at a fork (plot no. 61), turn right. Walk along the fields on the left-hand side while remaining inside the forest and, after a bend to the right, you will come to a crossroads (map).

Yellow markings (rare)

(4) Then take the first path on the right, which climbs between plots nos. 46 and 61. Further on, walk northwards, on fairly level ground, through a forest of oak trees. Ignore a path branching off to the right (plots nos. 47 and 61) and continue straight ahead. At a three-way junction (not shown on the map), turn left downhill.

(5) At the next fork, before leaving the forest (a few pine trees), turn right and walk up the edge of the forest with a beautiful sloping lawn on your left (viewpoint). Enter the forest again and wind your way through a forest of oak trees with a few beech trees. Descend under the pine forest, walk along a lawn on your left, ignore a path on your right and climb up the edge of the lawn on your left. Return to the forest and come out onto a sunken path descending from right to left.

No markings

On the following section, the path taken at the start and a few paths crossed further on are not shown on the IGN map.

(6) Cross the sunken path and continue straight ahead on a trail. Make a right turn and then continue north-east on a wider path. Ignore a path on the right and then, a few metres further on (large oak tree marked with the number 2), ignore a path on the left and continue north-east. At the boundary between plots 11 and 12, ignore a path on the right and descend gently into a beech forest. At elevation 115 (large beech tree on the left), turn right onto the path.

(7) At the next crossroads (plot no. 3), looking back, a sign tells us that we were following the Route Tournante. Then turn sharply left (old red cross). Descend along a path and pass directly below the large beech tree spotted earlier.

Yellow markings (rare)

(8) Find the marked path and follow it downhill to the right. At the bottom, at a T-junction, turn right. Walk along the bottom of a small valley and ignore the mountain bike tracks coming down from the right.

(9) Facing a forest barrier, turn right and, at the fork that immediately appears (not shown on the map), turn right uphill. At the next fork, turn left, pass under a power line in a clearing and then re-enter the forest. Descend, ending with a right-left turn.

(10) Pass a forest barrier on your right and continue north-east. Ignore a path on the right (not shown on the map), veer left and climb steeply. At the top of the hill, turn right, pass a three-trunk oak tree on your right and continue north-east. Pass a forest barrier and, at the T-junction immediately ahead, turn right. This will take you to Carrefour Henry.

No markings

(11) At Carrefour Henry, go through the forest gate and continue straight ahead, leaving plot no. 20 on your left. Follow the east-southeast path marked with yellow signs with two sides, through a forest of oak and birch trees.

(12) At the crossroads (plots 21 and 23), take the first path on the right (south-east). At the junction with a forest track (large central circle), continue straight ahead on a wide, open path.

(13) At the next junction (plots nos. 41A and 40A), turn left onto a shaded path. At the Grand Maître crossroads (plots nos. 43 and 42), turn right (south-east) onto a wide path. At the next crossroads (plots nos. 72 and 52), continue straight ahead and pass a small pond on your right.

(14) At the next crossroads, continue straight ahead and begin to descend gently. Further on, the descent becomes very steep. At the bottom, turn left, cross a stream and cross the D114 (take care).

(15) Follow the D114 to the right and, after a few dozen metres, take the small road on the left towards Apremont. Ignore a street on the right, enter Apremont and ignore another street on the right. At the stop sign, turn right into Rue du Manoir and you will quickly find the car park (S/E).

Waypoints

  1. S/E : km 0 - alt. 55 m - Apremont - Rue du Manoir
  2. 1 : km 1.72 - alt. 134 m - La Belle Côte
  3. 2 : km 2.39 - alt. 151 m - Carrefour Dauphine - Map
  4. 3 : km 2.99 - alt. 134 m - Mare du Désert
  5. 4 : km 3.83 - alt. 118 m - Crossroads - Map
  6. 5 : km 4.73 - alt. 127 m - Fourche - Calcareous grassland
  7. 6 : km 6.21 - alt. 124 m - Crossroads
  8. 7 : km 7.85 - alt. 113 m - Crossroads with the Route Tournante
  9. 8 : km 8.23 - alt. 88 m - Crossroads
  10. 9 : km 9.11 - alt. 60 m - Fork in the road - Forest barrier
  11. 10 : km 9.72 - alt. 87 m - Forest barrier
  12. 11 : km 10.29 - alt. 113 m - Henry crossroads
  13. 12 : km 11.06 - alt. 119 m - Carrefour de la three-way junction
  14. 13 : km 11.61 - alt. 122 m - Crossroads
  15. 14 : km 13.12 - alt. 120 m - Carrefour du Gouverneur
  16. 15 : km 13.85 - alt. 44 m - Route D114
  17. S/E : km 14.8 - alt. 55 m - Apremont - Rue du Manoir

Practical information

Hiking boots required. Some sections may be muddy in wet weather.

No drinking water sources identified along the route.

A 1:25,000 map is essential (at least the one accompanying this description).

Hike completed by the author on 23 April 2017.

In the nearby area

- Pleasant forest trails.
- Some remarkable trees.
- Calcareous grasslands between (4) and (6).

Reviews and comments

4.7 / 5
Based on 19 reviews

Reliability of the description
4.7 / 5
Clarity of route map
4.6 / 5
Route interest
4.6 / 5
severine Machefert
severine Machefert

Overall rating : 4.3 / 5

Date of walk : Feb 15, 2025
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★☆ Good
Route interest : ★★★★☆ Good
Busy trail : No

A very beautiful hike in the woods with varied trails. Lots of fallen trees and mud in some places. A guaranteed return to nature.

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ealet
ealet

Overall rating : 4.7 / 5

Date of walk : Aug 21, 2023
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★☆ Good
Busy trail : No

A very pleasant forest trail on a sunny day, with a well-marked route that is easy to follow
we were also lucky enough to see some deer
thanks to the author for sharing this

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randolim78
randolim78

Overall rating : 5 / 5

Date of walk : Jul 23, 2023
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good
Busy trail : No

A pleasant hike with no issues; the directions are very clear. We completed it in warm weather, and the icing on the cake was seeing several deer on multiple occasions. Thank you for this hike.

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optimus prime
optimus prime

Overall rating : 5 / 5

Date of walk : Jun 24, 2023
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good
Busy trail : No

Which hike should you choose when the thermometer is hovering around 35°C? A hike in the forest, somewhere peaceful. Forget the forests of St Germain or Rambouillet.
It will be the forest of Rosny sur Seine.
A very pleasant hike (already done in 2019) that is 90% in the shade. The paths are varied, ranging from undergrowth trails to wider paths, but always in the shade. The forest is also varied in appearance. Woods, high forests, meadows and even passages through pine forests (where the smell of pine trees amplified by the heat almost reminds us of the trails in the Esterel).
We only encountered two couples of hikers. And no one during our lunch break.
An easy hike, as always well described by Nétra.
There was only one moment of hesitation, 150 m at the fork after point 7, on the descent, when we had to take the left path. But even if you take the wrong path, you will reach the perpendicular path below.
Thank you, Etienne

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sylmar27
sylmar27
• Last modified:

Overall rating : 4.7 / 5

Date of walk : Nov 12, 2022
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★☆ Good
Busy trail : No

hello,
after checking out this hike in August with my wife, we did it with our group of friends.
It was a shame that the fog lingered all morning, but the picnic next to the wash house was warm thanks to the group's good spirits, even if the air temperature was less so.
A beautiful hike that I highly recommend

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sylmar27
sylmar27

Overall rating : 5 / 5

Date of walk : Aug 27, 2022
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good
Busy trail : No

a very beautiful hike and the directions provided are reliable and detailed. I misinterpreted point 12, but it didn't matter much as I was able to correct myself using my GPS. You do indeed need to turn right, but I would add "the open lane".
Having mapped out the route too quickly at the start, I actually left the wash house on the right and climbed the embankment a little further on the left to come out onto a field with a path running alongside the stream. At the edge of the woods, turn right and climb a path, then continue to the D114. I appreciated my mistake because you walk much less on the tarmac of this D114.
It's a bit challenging in places, but you don't meet many people except for a few mountain bikers
I highly recommend it.
Happy walking, everyone!

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Nathaelle95
Nathaelle95

Overall rating : 4.7 / 5

Date of walk : Jul 29, 2022
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★☆ Good
Route interest : ★★★★★ Very good
Busy trail : No

A very beautiful hike, the forest is magnificent and we hardly saw anyone... except for a small deer and some frogs lounging around the pond
The route is well marked on the app, but we took a wrong turn at one junction – these things happen.
The whole hike took us four hours. It was very hot, so it was nice to be in the forest (there are also some paths without shade, but they are rarer).
Happy hiking, everyone!

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FEUILLARD
FEUILLARD

Overall rating : 4.3 / 5

Date of walk : Jun 13, 2021
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★☆ Good
Route interest : ★★★★☆ Good
Busy trail : No

A very beautiful hike.
In this heat, we appreciated the shade of the forest.
Thank you to the creator of this route.

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IDEGALARME
IDEGALARME

Overall rating : 4.7 / 5

Date of walk : Jul 19, 2020
Reliability of the description : ★★★★☆ Good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good
Busy trail : No

Beautiful forest with remarkable trees and deer. Picnic by the desert pond. Challenging but wide trails. Covered 19 kilometres without getting lost, with two breaks. Good walk.

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sissidanseuse
sissidanseuse

Overall rating : 4.3 / 5

Date of walk : Jun 03, 2020
Reliability of the description : ★★★★☆ Good
Clarity of route map : ★★★★☆ Good
Route interest : ★★★★★ Very good
Busy trail : No

beautiful route. But when you get to the Henry crossroads...problem: no more landmarks, we had to backtrack to find the route... difficult... after several trips back and forth, we found our way out thanks to the GPS! A shame, but luckily the rain that had been forecast didn't materialise, so it was still enjoyable! A total of 23 km. Maybe we'll do it again?

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optimus prime
optimus prime

Overall rating : 5 / 5

Date of walk : Jul 06, 2019
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good

Another beautiful walk in the forest. In these hot days, this forest seems less cool than https://www.visorando.com/randonnee-l-eta....The route is varied and, with a bit of luck, we may come face to face with some of the "owners" of the place.
Once again, thank you Netra for this detailed description

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krisstoof
krisstoof

Overall rating : 4 / 5

Date of walk : May 12, 2019
Reliability of the description : ★★★★☆ Good
Clarity of route map : ★★★★☆ Good
Route interest : ★★★★☆ Good

a beautiful route through a very pretty parish-specific to Brittany forest!

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Taton27
Taton27

Overall rating : 5 / 5

Date of walk : Mar 25, 2019
Reliability of the description : ★★★★★ Very good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good

Excellent walk. Much appreciated for the different species of trees encountered
As it was logging season, we still had to contend with muddy sections.

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JLEWD
JLEWD

Overall rating : 4.7 / 5

Date of walk : Sep 15, 2018
Reliability of the description : ★★★★☆ Good
Clarity of route map : ★★★★★ Very good
Route interest : ★★★★★ Very good

A very pleasant route through the forest. Varied terrain and precise descriptions. I recommend it.

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