Calanques National Park protects twenty kilometers of Europe's only temperate-zone fjords, where Jurassic limestone plunges 400 meters into the Mediterranean between Marseille and Cassis. Declared a UNESCO Biosphere Reserve in 2009 and a national park in 2012, the site harbors 140 protected species including Bonelli's eagles, Yelkouan shearwaters, and endemic rock-dwelling plants found nowhere else on Earth. The word calanque derives from the Provençal calanca, meaning steep-sided inlet; geologists confirm these formations began as river valleys carved during the Messinian Salinity Crisis six million years ago, then flooded when sea levels rose after the last Ice Age. The park's turquoise waters owe their clarity to minimal agricultural runoff and strict anchoring regulations enforced since 2012. Daily vessel quotas prevent mooring damage to Posidonia oceanica meadows, submarine grasslands that oxygenate the water and shelter juvenile fish. Calanque d'En-Vau, accessible only by sea or a two-hour scramble over scree, features a 200-meter-wide beach hemmed by 300-meter cliffs; its eastern wall displays horizontal strata recording 140 million years of sediment deposition. Calanque de Sormiou, the largest at 1.2 kilometers long, shelters the submerged Cosquer Cave, whose Paleolithic paintings 37 meters below the surface prove sea levels stood 135 meters lower 27,000 years ago. Modern catamaran excursions depart from Marseille's Vieux-Port, passing the 17th-century Fort Saint-Jean and Pharo Palace before reaching open water. Twin-hulled vessels draw less than two meters, permitting anchorage within fifty meters of shore where monohulls cannot venture. Operators schedule departures between April and October; July and August see afternoon winds called the Mistral reach 40 knots, making morning sailings preferable. Half-day itineraries typically include three swimming stops — Calanque de Sugiton, Calanque de Morgiou, and Île Maïre's southern cove — with durations ranging from four to six hours. Full-day routes extend to Cassis, adding Calanque de Port-Pin and the natural arch at Calanque d'En-Vau, where crews serve rosé from Bandol AOC vineyards and platters of tapenade, socca, and bouillabaisse terrine prepared by Marseille provisioners.