The delta, opening of the Leyre on the Bassin d'Arcachon, is composed of multiple places where stable parts are juxtaposed occupied by salt meadows, dammed areas, reedbeds, grazed meadows and sectors subject to the dynamics of the tides. , sandbanks and mudflats. The fresh water of the river and the salt water of the ocean come together and are conducive to the establishment of specific species. Situated on one of Europe's most important flyways, it is truly the domain of birds. A 9 km circuit allows you to discover the gallery forest along the Leyre and the humid plains surrounded by marshes further downstream.