Rivers and wetlands

From the Rance Valley to the 'Marais Blanc'

The country around Saint-Malo and the Bay of Mont-Saint-Michel is full of hidden treasures for those taking the time to get away from the coast a little. The Rance Valley, the lakes of the Mesnil forest and the vast expanses of the Marais Blanc on the edge of the waterways.

The Rance estuary

The Rance Valley is a tourist attraction on its own. To fully discover it and admire the historical heritage of its countryside, enjoy a boat trip from Saint-Malo to Dinan. The Rance, a coastal river a hundred miles long, rises in the Côtes-d'Armor and empties into the English Channel.

The village of Saint-Suliac

Located on the right bank of the Rance, the former fishing village of Saint-Suliac is ranked among the most beautiful villages in France. You'll be utterly charmed by its picturesque look. Here, fishing nets cling to the facades of granite houses, nestled in streets so narrow that we call them alleys. The church, its enclosure and its portals are registered historical monuments.


The lakes of Mesnil forest

The Saint-Malo drinking water reserves come from the Mireloup and Beaufort lakes in the Mesnil forest. Freshwater fishing is permitted all year round. Each lake has its speciality - trout and pike fishing on Mireloup while at Beaufort, the carp is king.

Walkers will adore the walk around Mireloup, an 18 km loop from Le Tronchet. It crosses the Mesnil forest and joins the two lakes of Mireloup and Beaufort.


The village of Le Tronchet is located 25 kilometres from Saint-Malo. It is crossed by a watercourse, the Meleuc. This brook feeds three lakes: the Laurel, the Abbatiale and Mireloup. The latter two are connected together by a canal and represent an area of ​29 hectares.

Fishing on lake Beaufort

A beautiful lake of 33 hectares, located in the town of Plerguer, north of Le Tronchet. It has excellent carp, with specimens that can weigh up to eighteen kilos! Fishing by daylight only.

The wetlands of Mont-Saint-Michel bay

The Dol salt marshes in the Bay of Mont-Saint-Michel are one of its main environment types. They form an incomparable landscape, with different zones called the Marais Blanc and the Marais Noir.

The marais blanc

Ground at sea level, born from the retreat of the ocean: the Marais Blanc takes its name from the colour from the earth, tinted by the marine alluvium, a highly calcareous sand made of shell dust.

The Marais Blanc stretches around the entire bay of Mont-Saint-Michel. Go for a walk, along the canals and channels to observe the particular flora of the marsh, characterised by rows of willows and poplars ...

The marais noir

The Marais Noir is an environment of peat soils. It features numerous lakes and ponds, and a large number of poplar trees.

It has always been a sort of a "secret" part of the marshlands because it is so difficult to get to. You can find these landscapes around Châteauneuf-d'Ille-et-Vilaine.

Combourg Lac Tranquille

The Lac Tranquille is a 22 hectare lake, located at the foot of the Combourg castle in Romantic Brittany. In his ‘Mémoires d’Outre-Tombe’ (Memoirs From Beyond the Grave), the celebrated author François-René de Chateaubriand recalls the lake as follows: "Do you remember the Lac Tranquille that the swift swallow grazed, the swaying reed curving in the wind, and the beautiful sunset over the water”.
From the banks, we can enjoy very pretty viewpoints of the castle and the little characterful city that cuts into the side.
A developed path allows you to walk around the lake. On the north bank, you can follow the Chateaubriand trail where eleven desks will guide you through the author’s life. You can also follow the literary trail which will immerse you in the works of great romantic authors, all the while allowing you to discover the plants and wildlife of the lake banks.

The Rigole de Boulet (The Boulet Channel)

Created in the Napoleonic era, it was used to supply water to the Ill-et-Rance canal in its highest reaches, from the Etang de Boulet (Boulet Lagoon) in Feins to the Ecluse de Villemorin (Villemorin lock) in Guipel. Entirely man-made between 1804 and 1832, it winds through the Dingé countryside for 14 of its 17 kilometres.

This long channel crossed through the wooded countryside and wetlands, often fragmenting them, and forced the network of natural waters to pass underneath, hence the small engineering structures such as siphons, weirs and aqueducts, as well as the bridges and footbridges that restored surface traffic. The fill and rubble needed to form the banks, and the successive planting of lines of trees along the riverbank boundaries, have transformed this long stream into a distinctive, intimate, shady landscape, that has been passed down to us.

This constructed heritage is nonetheless charged with a multifaceted history: technical and hydrographic. Connected to the canal and the development of the 19th century, this heritage was also witness to the ingenuity of maintenance systems, both human and ecological history, and the history of the people who built and used the canal. This memory is still present today, in our relationship to the water and its many uses: water conveyance, drainage, washing, fishing and games, abundant vegetation, diversified plants and wildlife.