L'Île-d'Olonne can be explored through three distinct themes: a landscape shaped by water, birdwatching in the marshes, and architectural history. Salt marshes and fishpond marshes now occupy the southern part of the commune. Historic buildings add tangible layers of the past to this picture. So this is not just about the landscape, but also about how it came into being and the traces left by the area's history.
Salt marshes and the history of the landscape
Until Roman times, the Havre de la Gachère was an ocean-facing gulf into which two rivers flowed. The salt marshes developed from a large lagoon that gradually silted up. People then created basins and canals connected to the ocean. Both natural change and human intervention are therefore part of the area's landscape history: the lagoon gradually silted up, followed by the creation of water basins and canals.
The salt workers at the Salorge de la Vertonne offer guided tours. Availability varies by season, so plan your visit according to the current schedule. The Observatoire d'oiseaux offers a different focus: naturalists lead birdwatching sessions over the marshes, using telescopes. Educational areas are dedicated to wild pollinators and wetlands. Opening periods vary by season, so plan your visit accordingly.
Buildings and traces of history
When the Église Saint-Martin-de-Vertou was extended around 1700, it was given a twisted spire, considered entirely exceptional in France. The Cave communale de l'Îlot Mandret preserves the remains of a 15th-century fireplace and a 16th-century beam. The Cave opens on certain occasions, including the Fête des Vieux Métiers, Heritage Days and summer tours organised by the tourist office, which must be booked in advance. Check the dates before visiting, as opening occasions may vary. In 2026, the Fête des Vieux Métiers in L'Île-d'Olonne celebrated its 44th edition.
The Moulin Gueffard also brings together architectural history and views of the landscape. It is one of the oldest mills in the Les Sables d'Olonne agglomeration. A document from 1656 mentioning the Moulin du Bourg suggests that the Moulin Gueffard already existed in the 17th century or earlier. The restored mill has a viewpoint, accessible via a central spiral staircase, offering panoramic views of the marshes and the village of L'Île-d'Olonne. As access conditions may change, it is advisable to check them before visiting.
Walks and cycle route
The Pont de la Salaire is a place for walks in the marshes and lies on the Vélodyssée cycle route. It therefore serves as a useful reference point both for walks through the marshland and for finding your way along this cycle route.
Each theme offers a different perspective: the development of the lagoon and salt marshes tells the story of the landscape, the Observatoire d'oiseaux focuses on observing nature, and the church, Cave and Moulin Gueffard bring dated architectural history into the picture. If you are planning a stay, these differences can help you decide whether to focus on nature, heritage or both.
Discover more destinations: Sainte-Flaive-Des-Loups, Grand'landes, Nesmy, Saint-Hilaire-De-Riez, Saint-Cyr-En-Talmondais, Bazoges-en-Paillers, Saint-Martin-des-Tilleuls, Vix.
For the broader travel overview: Vendée.
