MC Swim Challenge

Setting off from Plage du Bestouan in Cassis, swimmers take on 25 kilometers of deep azure water all the way to Marseille. The MC Swim Challenge is an endurance open water sea marathon held in the heart of the Parc National des Calanques along the coast of Provence in southern France. Swimmers cover a full 25-kilometer point-to-point journey traversing one of the Mediterranean's most dramatic coastal wildernesses. This is an expedition reserved strictly for confirmed endurance athletes ready to spend between 8 and 10 hours in the open sea. The field is limited to eighty swimmers divided into five cohesive teams who advance together through the swells. Safety on such an immense coastal passage requires dedicated logistics.

Organized by the École de Sauvetage Côtier Méditerranéenne, every single team is shadowed stroke for stroke across the gulfs. Each pod swims alongside an assistance boat staffed by three volunteers, a dedicated rower pacing just off the swimmers' shoulders, and an attending medical vessel keeping watch over the entire armada.

From Port-Miou to En-Vau: the narrow fjord inlets

The route opens just outside Cassis as swimmers sweep past the entrance of Port-Miou, a winding 1.4-kilometer inlet. For generations its white Urgonian stone was quarried for industrial soda production until operations ceased in 1982. Today the former dwelling of the quarry miners on the quayside has found new life as the harbor master's office. At Calanque de Port-Pin twisted Aleppo pines surround a gently sloping cove with an unsupervised sandy beach. Soon the walls rise dramatically higher as you cross the threshold of Calanque d'En-Vau. Massive sheer cliffs tower over the water, framing a secluded pebble beach hidden at the end of the chasm.

Morgiou and the submerged entrance of Cosquer Cave

Deep below the surface near Pointe de la Voile and Cap Morgiou rests one of the world's most astonishing archaeological wonders, the prehistoric Cosquer Cave. Its decorated chambers contain ancient rock drawings that survived the millennia with the cave's entrance sitting 37 meters underwater. The cave is reached through an underwater tunnel of 175 meters. To protect both human lives and the fragile Paleolithic art, authorities established a strict maritime exclusion zone prohibiting all diving and anchoring within a 500-meter radius around Pointe de la Voile, and in 2015 the submerged entrance was permanently sealed behind solid stainless steel grilles.

Inside the sheltered basin of Morgiou itself sits a timeless Mediterranean hamlet. Small cabins line the cove, having evolved from simple commercial fishing shelters into cherished seaside retreats. This quiet inlet once staged grand maritime history: in 1622 King Louis XIII visited the calanque to observe a massive traditional tuna-netting event.

Sugiton and Sormiou: submarine springs and traditional cabanons

The sea at Calanque de Sugiton can suddenly feel distinctively colder on the skin. Shaded by towering cliffs and stirred by the mistral wind, these waters are directly chilled by freshwater springs bubbling up from the seabed. Rounding into the Calanque de Sormiou, the landscape broadens between the crête de Morgiou and the crête de Sormiou. Beneath your stroke, the underwater drop-offs and rocky seabed reveal high ecological richness, teeming with biodiversity along the cliff faces. Sormiou preserves an authentic coastal village nestled behind a small protective seawall, centered around a compact 61-meter beach. Row upon row of roughly one hundred traditional cabanons line the cove, standing as living emblems of Marseille's traditional coastal culture.

The Riou Archipelago: seabird sanctuaries and ancient wrecks

The southern faces of the Riou Archipelago feature precipitous walls that plunge straight down into deep blue offshore water. These islands have witnessed thousands of years of Mediterranean seafaring. Around 5600 BC in the Neolithic era, lower sea levels meant the archipelago was actually a peninsula reachable on foot from the mainland. In later centuries terracotta remains reveal that both Etruscan and ancient Greek sailors used the islands, while from 1295 until 1695 Riou maintained a crucial coastal surveillance lookout guarding the approaches to Marseille. The surrounding sea has yielded world-famous underwater discoveries. In 1952 Jacques-Yves Cousteau conducted a sustained surface-supported underwater archaeological excavation at the Grand Congloué site just off Riou's shore. Today the archipelago is an undisturbed nature sanctuary of international significance.

The limestone ledges host one-third of the total French population of Cory's shearwaters, and alongside Corsica it remains the only breeding ground in France for the Mediterranean shag. Accompanied by the calls of seabirds wheeling above the cliffs, swimmers power through the final stretch of sea, leaving the wilderness behind as the welcoming harbor of Pointe Rouge comes into view.