Île de Ré tide times

Île de Ré is a low-lying limestone island 30 km long and at its widest 5 km across, connected to La Rochelle by a 3 km toll bridge since 1988. The island sits in the Pertuis Breton — the channel between the mainland and the open Charentaise coast to the north — and faces southwest into the Atlantic across the Pertuis d'Antioche. The tidal range of approximately 5.0 m mean (with spring tides reaching 5.5–5.8 m) shapes every part of the island's geography and economy. At high water the island's salt marshes fill; at low water the eastern and northern intertidal zones expose mudflats that run several hundred metres offshore.

The 170 km of cycling paths on Île de Ré are the island's defining leisure infrastructure. Routes range from the main D735 artery through the centre to narrow dike paths running along the salt-marsh edge of the intertidal zone. The dike paths are the ones worth seeking out: at low water on a spring tide, cycling the eastern coast of the island puts the retreating sea and the exposed oyster tables 10 metres to the right of the handlebar. The intertidal landscape visible from the dike path — bouchots, oyster concessions, wading birds, salt pans — changes with every tidal cycle and every season.

The mussel and oyster production on Île de Ré is among the most significant in France. The oyster concessions are arranged in the intertidal zone as flat tables, covered at high water and accessible to the operators at low water. The mussels grow on bouchots — wooden posts carrying rope-wound colonies — arranged in long rows perpendicular to the shoreline in water 0.5–2 m deep. Both products are directly tide-dependent: the operators' working windows are low water, reached in Wellington boots across the exposed flat or by flat-bottomed boat on the rise. The oyster-culture zone is visible from the bridge approach road, extending east of the island toward the mainland shore.

The salt pans (marais salants) occupy the interior of the island behind the Atlantic dune system on the western coast. The pans fill from the sea via channels and sluices that operate on tidal cycles; the salt harvest — grey sea salt (sel gris) and the premium fleur de sel crust — is collected manually in summer. The fleur de sel forms only on calm days with low humidity when the surface evaporation rate is right; harvest is by hand with a wooden skimmer and is collected twice daily near the neap low-water period. A small producer industry of salt farms, some open for visits, operates across the southern and central interior.

Saint-Martin-de-Ré, the principal town, has a Vauban-designed fortification that encircles the old harbour — a UNESCO World Heritage Site since 2008 as part of the Vauban fortifications network. The harbour itself is tidal: the inner basin dries at low water on spring tides; the outer harbour (the avant-port) remains navigable through most of the tidal cycle. Visiting yachts berth in the outer harbour and time entry or exit by the tide. The fortified ramparts above the harbour give a 360-degree view over the Pertuis Breton, the bridge, and the Atlantic horizon.

For wildlife, the intertidal mudflats on the island's eastern coast and the salt-marsh channels behind the dunes on the west side together make Île de Ré one of the most important shorebird staging areas in western France. In autumn (August–November), tens of thousands of dunlin, knot, and bar-tailed godwit use the eastern flats as a feeding stop. The Fier d'Ars, a long tidal inlet at the island's northwest tip, holds a nesting colony of the Mediterranean gull and a regular wintering population of avocet. The tidal rhythm of the Fier — filling and draining through a narrow channel twice daily — determines when the mudflat is exposed and when the birds can feed.

Tide data for Île de Ré comes from the Open-Meteo Marine API (±45 min / ±0.2–0.3 m). SHOM authoritative tables for Saint-Martin-de-Ré are the navigation-grade reference.