The Aven du Trou du Duc

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This is an easy hike that allows you to discover an old railway line and its tunnel, as well as a geological curiosity, while enjoying the natural heritage of the Hérault hinterland.
Moderator's warning: Please note that reviews of this hike indicate that a GPS or the Visorando app is useful

Details

n°1803536
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  • Walking
    Activity: Walking
  • ↔
    Distance: 3.00 mi
  • ◔
    Average duration: 1h 40 
  • ▲
    Difficulty: Easy
  • ⚐
    Back to start: Yes
  • ↗
    Ascent: + 302 ft
  • ↘
    Descent: - 295 ft
  • ▲
    Highest point: 545 ft
  • ▼
    Lowest point: 348 ft
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Photos

Start of the walk
Old railway line
Road after tunnel
The tunnel

Description of the walk

Park along the D30, Route de Villeveyrac. There is a large parking area on the side of the road before the first houses of the village of Saint-Pargoire.

(S/E) Take the path on the left heading south-east.
Continue along this path and ignore the first junction with another path on the left. You will come to the old railway line, which you should follow. You will reach a junction with a farm track, where there is an abandoned house.

(1) Stay on the railway line until you reach a tunnel. Go through the tunnel and about 100 metres after the exit, turn right twice to take the path that goes uphill.

(2) At the top of the hill, at the crossroads, take the path on the left that passes in front of a ruined house. Ignore the two paths on the left and continue until you reach a fork.

(3) Take the path on the right, which continues along the vineyards
Continue along this path in the same direction until you reach the abandoned house you passed earlier. Turn right.

(1) Cross the old railway line and follow the tarmac road that climbs alongside the woods. You will reach a wide right-hand bend.

(4) Leave the road and take the path opposite. Follow it until you reach a junction with a wider path on the right. Here you will find the Aven du Trou du Duc, a large natural hole in the ground.
For obvious safety reasons, do not attempt to climb down into the hole.

(5) Ignore the path that branches off to the right and continue along the small path until you pass a ruin on the left and reach the D30 road a few metres further on.

Turn left and follow the road until you reach the car park (S/E).

Waypoints

  1. S/E : mi 0 - alt. 417 ft - D30 car park
  2. 1 : mi 0.81 - alt. 440 ft - Railway crossing
  3. 2 : mi 1.46 - alt. 518 ft - Path on the left
  4. 3 : mi 1.7 - alt. 495 ft - Trail junction
  5. 4 : mi 2.18 - alt. 463 ft - Road/path junction
  6. 5 : mi 2.44 - alt. 522 ft - Aven du Trou du Duc
  7. S/E : mi 3 - alt. 417 ft - D30 car park

Notes

Some areas may be rocky, so good footwear is necessary.
A torch is also required to pass through the tunnel.

Worth a visit

The main attractions of this hike are the old railway tunnel and the karstic cave of the Trou du Duc. However, don't forget to pay attention to the landscape and geology of the area, which are quite diverse along this route.

Reviews and comments

4.2 / 5
Based on 29 reviews
Reliability of the description
4 / 5
Ease of following the route
4.2 / 5
Route interest
4.3 / 5
User 28834802

Overall rating : 4.7 / 5

Date of your route : May 04, 2026
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

Really nice! No signposts, but luckily there’s the app… the SNCF signs raise questions about the right of way for walkers… worth doing again!

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User 25481417

Overall rating : 3.3 / 5

Date of your route : May 03, 2026
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★☆☆☆ Disappointing
Route interest : ★★★★☆ Good
Very busy route : No

The hike would have been great, but I had to keep track of my progress on my phone because the signposting is virtually non-existent; without a GPS or the Visorando app, the route would have been impossible to follow.
Some sections would benefit from being re-graded as they’re badly damaged by quad bikes.
The SNCF signs in place raise questions about the right to use the path.
Apart from these comments, the walk is lovely with some beautiful views.

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Vissou74
Vissou74

Overall rating : 4.3 / 5

Date of your route : Jan 25, 2026
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★☆ Good
Very busy route : No

The "abandoned house" in 1 is undergoing renovation.
There was a lot of water on the paths following the heavy rains of the last few days, so we had to leave the path several times, but without losing track of the route. The Trou de Duc karstic cave is not particularly well signposted, but fortunately a splash of fluorescent paint helped us to find it.

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User 17119727

Overall rating : 5 / 5

Date of your route : Jan 19, 2026
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

Easy walk and the hole is a curiosity. The old railway crossing is also a curiosity worth seeing.

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User 15982374

Overall rating : 4.3 / 5

Date of your route : Dec 01, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

A very interesting hike.
Be aware that walking on the old railway track can be hard on your ankles.
It's juniper berry season. We picked berries near the karstic cave.

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georgevelyne@gmail ;com
georgevelyne@gmail ;com

Overall rating : 5 / 5

Date of your route : Nov 20, 2025
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

A very pleasant short hike that takes us through an old SNCF railway tunnel. Be careful, just after the tunnel, there is a short steep climb on the right, but it is not particularly difficult.
Thanks to the author of this beautiful walk.

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User 19982868

Overall rating : 4.7 / 5

Date of your route : Sep 28, 2025
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

A lovely little hike, with no particular difficulties, completed in 1 hour and 40 minutes, near Valmagne Abbey. I would be curious to know the origin of the name "trou du Duc" (Duke's hole) for the entrance to this karstic cave!

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pierrette8189
pierrette8189

Overall rating : 5 / 5

Date of your route : Apr 14, 2025
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

Pleasant and diverse landscapes

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Philippe Vaugrente
Philippe Vaugrente

Overall rating : 3.3 / 5

Date of your route : Jan 13, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★☆☆☆ Disappointing
Route interest : ★★★★☆ Good
Very busy route : Yes

Hello

A hearing aid for changing paths would be appreciated

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JF34230
JF34230

Overall rating : 4 / 5

Date of your route : Dec 12, 2024
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★☆ Good
Very busy route : No

Dangerous! No warning signs, no protective barrier around the hole at ground level.

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Nop
Nop

A pleasant walk.
It would be interesting to have other walks around this site with different durations. The site offers exceptional views.

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jean marie di pizzo
jean marie di pizzo

Overall rating : 4.3 / 5

Date of your route : Nov 20, 2023
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★★ Very good
Very busy route : No

hike to be enjoyed in the sunshine to appreciate the different landscapes

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jdelettrez
jdelettrez
• Edited:

Overall rating : 4.7 / 5

Date of your route : Jan 30, 2023
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

Three comments on this interesting route:
1) SNCF signs are posted along the old railway line. They warn that using this old track is prohibited and punishable by a fine. (They are not visible in the photos in the guidebook.) And this despite the fact that the site is not particularly dangerous. Thank you, SNCF, for covering your back at little cost!!!!!!! ,
Instead of blocking off one of its industrial wastelands, it could showcase it like it does in many other places.
But despite everything, this calls into question the legality of this route for those who are sticklers for the rules.
2) The end of the dangerous route along the road can be avoided. To do this, when you reach the road, cross it, go over the shallow ditch and follow the edge of the vineyard on the left. Cross the small road and go up into the next vineyard. Follow the edge, at the end turn right for 20 metres, a passage in the embankment leads to the path that goes down to the car park.
3) This route can be extended by 1.6km via a place called "L'Escuret":
At the tunnel exit, turn right then left(leaving the route), go down the stony path for 400 metres, ignoring the first path on the right and following the second on the right before the quarry. (coordinate 104 on the map)
Follow this new path to the tarmac road. Turn right towards Mas Nègre. 200m before the farmhouse and at a left-hand bend ( point 119 on the map), climb up to the right along a fallow field. At the right-hand corner, a slightly overgrown path will take you back to the vicinity of the point (3) ( you will rejoin the route)

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Ofir-67210
Ofir-67210

Overall rating : 3.7 / 5

Date of your route : Nov 05, 2021
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★☆☆ Average
Very busy route : No

The two points of interest, the tunnel and the karstic cave, are well worth seeing and quite unusual.
Bear in mind that the access path is very stony (ballast) and that some sections are quite tricky (steep): take care not to twist your ankles.

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Romain34230
Romain34230
• Edited:

Overall rating : 4 / 5

Date of your route : Jul 31, 2021
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★☆☆ Average
Very busy route : No

A pleasant little walk early in the morning. Nothing exceptional, but the charm of the garrigue is very much present.
As indicated in the route description, be sure to wear good walking shoes.

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