From the Arzal dam to La Roche Bernard along the left bank of the Vilaine

Start at the car park at the Arzal dam, on the left bank of the Vilaine.

The walk follows the^{GR®34–GR®39}route, which is very well signposted in red and white. The signposting is in excellent condition and easy to follow (as of April 2021).

(S) Head up towards the left bank and admire the base of the cliffs, at both high and low tide. Cross the road carefully and go up to the left along the path to take the road to the port. Follow the Vilaine all the way around the port; at the end, take the small footbridge and turn left at the end of the bridge. Follow the banks of the Vilaine upstream, then turn left to reach the Kerosten stream.

(1) Stay along the riverbank. Pass a developed area, then walk to the right along the fence of the drinking water treatment plant. At the entrance to the drinking water treatment plant, turn left onto the small road
At the end of the road, go down a flight of steps to the banks of the Vilaine; here you can enjoy a magnificent view of the river and a beautiful property on the opposite bank.

(2) Continue along the^GR® trail, moving away from the riverbank to reach the village of Le Cossois.

(3) Turn left twice in the village. Return to the riverbank at a designated rest area. Continue on to reach and pass through the village of Kernelo.

(4) Continue along the^GR® trail, following the red and white markings, to reach the Étier du Rah-Coët, a tributary of the Villaine.

(5) Cross it via the bridge and continue left to rejoin the banks of the Villaine at a place called Buttes du Rosquet. Leave the Villaine again to reach the village of Rosquet.

(6) Continue on, rejoin the riverbank and arrive at a magnificent view of the Port du Rodoir.

(7) Turn right to cross the Ruisseau de Rodoir a little further upstream. Then turn left, walk along the harbour and pass at the foot of the Ruicard rocks. Then walk along the harbour at La Roche-Bernard and reach the car park.

(E) Follow the road away from the river. After about fifty metres, turn left onto a path leading to the La Roche-Bernard bridge.

(8) Go under the bridge and join the^GR®349here. Continue along the Vilaine, which flows quietly below on the left.

(9) Turn left at the hamlet of La Ville Izac. You’ll come out onto a road; follow it to the left as far as the Moulin de Bourigan. At the junction, turn left to reach the Morbihan Bridge on the four-lane road (N165).

(10) Take the stairs to cross the Vilaine beneath the road deck; it’s a very pleasant crossing. On the other side, at the bottom of the stairs, turn left and follow the Vilaine on your left. Alternate between ascents and descents to reach the old bridge.

(11) Pass under the old bridge, turn right and head up onto the road at the old bridge. Cross the road carefully, keep to the right and head back up to find the path leading to the Roche Bernard bridge a few metres further up.

(12) Cross the bridge, staying on the pavement. Take care here: the crossing is not pleasant, there are no railings and vehicles travel fast. On the other hand, the view is stunning.

(8) At the end of the bridge, turn right down the steps. Follow the path you took on the way there in the opposite direction to return to the harbour (E).

The entire walk is 15 km long: 10 km to reach the port of La Roche-Bernard and 5 km for the circular route around the two bridges.

Arrangements for the return journey:
- Unless there is a health crisis, it is possible to travel down the Vilaine on the Yellow Boats.
- By car, arrange for at least two vehicles or for someone to provide a shuttle service from the port to the dam.

(7) Port de Rodon: picnic area with tables and benches. There was also a bar selling drinks and takeaway food from 11 am to 3 pm when we were there.
(E) If you’ve still got the energy, you can finish off with a visit to the old town of La Roche-Bernard.