Tremiti – Italian Open Water Tour

Across the turquoise straits separating San Domino, San Nicola, and Cretaccio, swimmers navigate the open Adriatic waters where Homeric legend placed the resting site of Diomedes. Known as the Traversata di Diomede, this open water swimming race organized by the Italian Open Water Tour takes place in the open sea of the Tremiti Islands, off the coast of Puglia. The stage gathers swimmers in late May to take on dramatic maritime routes across one of Italy's most secluded island groups. The competition program unfolds over an entire weekend in late spring, offering classic open-water distances of 6 km, 3 km, and the nautical mile of 1,852 meters, as well as a fast-paced 3 x 926 m team relay.

Swimmers chart courses through the lively inter-island channels, negotiating cross-currents that flow between the islands. While these channel currents require steady navigation and rhythm, the crossing remains well-contained between the island shores. In past editions, participants have encountered remarkably transparent sea conditions, with visibility plunging deep into wild underwater passages beneath sheer coastal headlands. The crystal-clear water and sheltered bays of the marine park provide an exceptional arena for swimmers facing the open sea. Cutting through the swells, you quickly discover that each island brings a completely different seascape, alternating between vertical rock ramparts, concealed sea caverns, and dense green pine canopies hanging over the waves.

Tremiti Marine Reserve: pristine straits and pelagic life

Rising from the Adriatic Sea off the Gargano coast, roughly 22 kilometres north of the Gargano promontory and 45 kilometres east of Termoli, the Tremiti archipelago comprises five distinct islands: San Domino, San Nicola, Capraia, Cretaccio, and the distant outpost of Pianosa. Swimmers compete within the Tremiti Islands marine nature reserve, a protected marine environment established in 1989 that covers 1,466 hectares of coastal waters and reefs. Below the surface, extensive meadows of Posidonia oceanica oxygenate the shallows and stabilize the seabed, creating thriving habitats where groupers, moray eels, and vibrant colonies of red gorgonians flourish along submarine ledges. The seabed around the islet of Cretaccio in particular has become a renowned haven for snorkeling thanks to its extraordinary density of marine life.

Rare Mediterranean monk seals have been documented surfacing in the reserve, with confirmed sightings concentrated around Punta del Cimitero and Punta del Faro on San Nicola Island. Along the maritime cliffs rising directly out of the water, the rocky slopes are dotted with wild caper bushes and fragrant rosemary plants.

San Nicola: cliffside abbey and centuries of naval sieges

The island of San Nicola presents an imposing natural fortress ringed by vertical cliffs that soar up to 60 meters above the waterline. Along its Acquedotto coastline, relentless storm surges driven by the Scirocco wind have carved deep wave benches and eroded dramatic rock faces over centuries. Centuries of Mediterranean seafaring left practical infrastructure embedded directly into San Nicola's coastal rock. Near the port, rock-cut rooms dating to the Roman period once served as warehouses for storing transport amphorae. In 1566, the fortress successfully repelled a fierce siege launched by the Ottoman fleet under the command of Piyale Paşa. During the Napoleonic wars, the stronghold faced further combat when French forces led by Murat successfully defended the garrison against an attacking English naval squadron in 1809. The modern settlement took shape in 1843, when King Ferdinand II of the Two Sicilies repopulated the archipelago by bringing in fishermen from the island of Ischia to harvest the rich offshore fishing grounds.

Capraia and Cretaccio: ancient myths and sunken landmarks

Cretaccio is the smallest island in the archipelago, covering approximately 4 hectares with a coastline extending for 1,300 meters. Cretaccio serves as a central stepping stone in the archipelago's waterways, sitting just 200 meters from San Domino, 300 meters from San Nicola, and 900 meters from Capraia. Less than 100 meters off Cretaccio's eastern tip, the rugged rocky outcrop of La Vecchia juts from the sea. Across the northern stretch of water sits Capraia, an uninhabited island with a land area of 45 hectares, a length of 1,600 meters, a width of 600 meters, and 4,700 meters of craggy perimeter. Ancient Greek voyagers named the island Aegylon, or Land of the Goats, around 1000 BC.

Today Capraia remains untouched by modern settlements, celebrated for its wild rocky landscape carpeted with mastic bushes, thistles, junipers, and sprawling caper plants. The cliffs of the archipelago are also home to the Diomedee of Diomedes. Beneath the surface off Capraia's coast, the sea holds modern wonders as well: since 1998, a three-meter-tall submerged statue of Padre Pio has stood on the seafloor at a depth of 14 meters, drawing free divers and snorkelers into its silent blue clearing.

San Domino: Aleppo pines, sea caves, and cove life

San Domino is the largest island of the Tremiti group, measuring 9,700 meters of coastal perimeter wrapped in a dense, fragrant pine forest. The woodland consists almost entirely of Aleppo pines mixed with aleccia, sweeping over the hills until the trees border the very edge of the coastal cliffs above the water. Ancient settlements also clung to this terrain, including Neolithic village sites dating to the seventh millennium BC discovered at Prato Don Michele, and a fourth-millennium BC village set on the maritime slope descending toward Cala Tramontana and Cala degli Inglesi. The Grotta del Bue Marino extends 70 meters into the cliffs, famous for the glowing blue reflections that dance across its interior waters.

The Grotta delle Viole takes its name from the deep purple-red hue created by encrusting calcareous algae that carpet its submerged rock faces. For swimmers finishing their crossing or resting between race heats, Cala delle Arene offers the archipelago's only sandy beach, featuring a shallow, crystalline seabed perfect for wading in. Cala Matano is a tranquil cove where songwriter Lucio Dalla composed some of his most famous songs. Emerging from the open channel into these sheltered waters, every stroke across the Tremiti straits links you to centuries of maritime life and Homeric sea myth.