Start on the wideGR®34path accessible from the D52 between Mesquer and Saint-Molf. Take the small road on the left towards Trévin, and turn right onto theGR®34. The wide path offers numerous parking spaces over 300 metres.
White and red markings
(S/E) Take the wide path towards Marais la Duchesse and follow it until you reach a fork where you cannot continue along the marsh, which becomes Étier de Boulay.
(1) Turn left onto the slightly uphill path, then right after 200 metres, and finally left to cross the pretty hamlet of Fontaine Bras. Take the first path on the right.
(2) Two alternatives:
- At low tide, at the intersection, leave theGR® which branches off to the left and take the path that runs alongside the Marais la Chouette. Go down the few steps to walk along the Marais Calza before joining theGR®34, which you will take to the right.
- At high tide, continue on theGR®34trail to the left, then take the small road to the right in the hamlet of Rostu.
(3) At low tide, leave theGR® to make a circular route via Île de Rostu. To do this, cross the bridge, then walk along the marsh on the right-hand side of the island. Follow the coastline, entering the enclosure through the gap in the fence, then exit the enclosure. Take the path that follows the marsh as closely as possible on your right until you reach a well-marked path that allows you to complete a circular route by returning to the Île de Rostu while walking alongside the fishing huts.
In any case, continue on theGR® trail that runs along the Notre-Dame la Sauvagère marsh and then the Étier du Goilé until you reach the Kervarin road.
(4) At the intersection, take the opportunity to admire the Port of Kercabellec by taking a 250-metre detour to the right along the small road.
Continue on theGR® via the Kervarin road until you reach the Cap Horniers road.
No signposts
(5) Turn slightly left and follow the D352 to the village of Mesquer.
(6) On leaving Mesquer, turn left onto Rue du Soleil, then left again towards the church on Rue du Midi. Turn right at the Town Hall square onto Avenue de Bretagne, which becomes Rue des Sports as it runs alongside the sports facilities in Mesquer. Pass the Vigne farm, cross the hamlet of Trévin and then Penloc via the Saint-Molf road to return to the starting point (S/E).