Charente-Maritime

Charente-Maritime occupies the northern arc of the Bay of Biscay coast above the Gironde estuary — a stretch of islands, straits, and salt marshes that has been shaped by a 5-metre tidal range for as long as the coast has been inhabited. The regime is semidiurnal and macrotidal: La Rochelle harbour records a mean range of approximately 5.0 m; Royan, at the Gironde mouth 80 km to the south, averages around 4.5 m. The result is a coast that changes character entirely between high and low water. Île de Ré, the island connected to La Rochelle by a 3 km toll bridge since 1988, is the department's most visited destination. Its mean tidal range of around 5.0 m exposes broad intertidal mudflats along the island's eastern and northern margins and drains the salt-marsh channels behind the Atlantic dune system to the west. The island's 170 km of cycling paths make it one of the most bike-friendly destinations in France; the flat terrain and the scale of the intertidal landscape give cycling here a coastal quality unlike anything inland. The salt marshes — marais salants — are worked as traditional salt-pans in the interior; the pans fill on the flood tide and are managed through the neap-spring cycle. The Pertuis d'Antioche is the channel between Île de Ré to the north and Île d'Oléron to the south. Tidal streams in the Pertuis run 1.5–2 knots in the main channel at mid-tide, and the passage is a significant navigational feature for coastal sailors and kayakers moving between the Atlantic coast and the inner Pertuis Breton to the north. Charente-Maritime's oyster and mussel aquaculture is among the most extensive in France. The concessions are laid out in the intertidal zone — tables and cages arranged on the mudflat that are covered at high water and accessible at low. The oyster harvest is tidal work; the schedule of every oyster farmer follows the tide tables as much as the clock. Royan, at the Gironde estuary mouth, is the southern anchor of the coast: a ferry connection to Pointe de Grave on the Médoc side of the estuary keeps cross-Gironde traffic moving independent of the bridge at Bordeaux, 60 km upstream. Authoritative tidal data for Charente-Maritime is published by SHOM. Open-Meteo Marine provides forecast reference for planning.