The 20-kilometre stretch between Marseille and Cassis holds Europe's only mainland calanques — steep-walled inlets carved into white limestone by millennia of wave action and tectonic uplift. Established as France's tenth national park in 2012, the 158-square-kilometre protected zone encompasses both terrestrial and marine territory, sheltering 140 terrestrial species and rare Posidonia seagrass meadows that anchor the Mediterranean ecosystem. The name derives from Provençal *calanco*, meaning a steep-sided rocky inlet, though geologists classify them as rias — drowned river valleys submerged when post-glacial sea levels rose 120 metres over 15,000 years. Cassis limestone, quarried here since antiquity, built Marseille's Vieux-Port quays and the Suez Canal's first lock gates. The rock's pure calcium carbonate composition yields the cliffs' signature white glare, visible from 30 kilometres offshore. Pine forests cling to ridgelines where Aleppo and maritime pines survived the last ice age in isolated refugia, their genetics now studied as climate relicts. Beneath the waterline, the park's marine zone protects 60 fish species and Europe's largest colony of Audouin's gulls, which nest on the Riou archipelago's car-free islands each spring. Access restrictions shape how visitors encounter the park. Road access ends at the Calanque de Sormiou; beyond that point, the coast remains roadless. Summer fire risk closes hiking trails from July through mid-September when the French fire-danger index exceeds three. This makes waterborne access the primary corridor for experiencing the park's deeper recesses during peak season. Electric propulsion rules now apply within the marine reserve's core zones, where internal combustion engines cannot operate between May and September to reduce acoustic disturbance to monk seal reintroduction sites. The park authority coordinates with 14 licensed operators who run scheduled departures from Marseille's Vieux-Port, Cassis harbour, and La Ciotat. Routes typically penetrate Calanque d'En-Vau, whose 400-metre cliffs frame a pebble beach accessible only by boat or a two-hour scramble, and Calanque de Sugiton, where freshwater springs create visible salinity gradients in the turquoise shallows.午後 departures catch the light when the sun illuminates the east-facing rock faces, revealing ochre and sienna strata within the Urgonian limestone.