OncoSwim

The waters off L'Estartit are defined by the interaction between the open Mediterranean and the sediment-rich outflow of the Ter River. As you push off from the beach at the start of the 30km OncoSwim, you will notice the water clarity shifting as you move away from 'la Gola', the river's mouth. This freshwater discharge is the reason for the fine, pale sand characterizing this stretch of the coast, though swimmers should anticipate variable surface conditions influenced by the river's flow and the prevailing coastal winds. Those familiar with the local calendar might find this long-distance challenge a distinct shift from the shorter, more contained swims nearby, such as the Travesía a nado Cala Montgó or the shorter Travesía Illes Medes - Estartit, which focus on the immediate archipelago surroundings rather than this coastal odyssey.

The marine reserve and the massif

Navigating toward the Medes Islands brings you into one of the most protected marine ecosystems in the Mediterranean. The seabed here is a complex landscape of tunnels and caves, though your focus will remain on the surface, where the protected status of the islands ensures a lack of boat traffic, allowing for a concentrated, rhythmic stroke. Beyond the archipelago, the route follows the rugged silhouette of the Montgrí Massif. These limestone cliffs plunge directly into the sea, creating a stark, vertical boundary to your right as you head south. Keep an eye on the skyline, where the unfinished silhouette of the 14th-century Montgrí Castle watches over the coastline, serving as a silent navigation point.

Logistics of the 30km challenge

The OncoSwim is an endurance event that requires mandatory team collaboration, whether you are swimming the full distance as a quartet or rotating via relays. The high registration costs, ranging from 750 to 1,500 euros depending on boat support, reflect the necessity of a dedicated escort vessel for each team throughout the 30km journey. This safety structure is essential given the exposed nature of the Costa Brava, where afternoon breezes can challenge even the most experienced swimmers. The day concludes at En Calau Beach in Calella de Palafrugell, a traditional fishing port that offers a sheltered finish after hours in the open sea. By the time you reach the final kilometers, you will pass the Formigues Islands, a small rocky chain that marks the final section before reaching the finish line alongside the participants of the 1.5km Solidary Mile.