Swim Alcatrazes

Swim Alcatrazes, an open water race around the Alcatrazes archipelago off São Sebastião, was established after the strictly protected conservation unit first opened its waters to visitation. Because the islands lie in an ecologically vulnerable and restricted maritime zone, staging the race requires formal authorisation from both ICMBio and the Brazilian Navy. To safeguard the marine reserve, participation is capped at an intimate total. Swimmers can choose between the 7-kilometre Ultra and the 3.8-kilometre Long course, with fields strictly limited to sixty and fifty athletes respectively. The journey begins on the sands of Praia do Perequê on the island of Ilhabela, where boats gather competitors during the January race window. Out around the islands, the course presents a rare open water test without a single reference buoy.

Swimmers must navigate entirely by reading the seascape, studying changing currents and winds while aligning their stroke against the natural contours of the cliffs. In past editions, participants tackled a combination of calm stretches and powerful ocean swells, including a narrow passage between rocks nicknamed the Garganta de Harry Finger, where currents rush with notable force. The line traces past the Ilha do Farol and the reef of Laje do Alagado before leading swimmers safely into the tranquil, transparent waters of Saco do Funil.

The submerged mountain ridges and depths of Alcatrazes

The dramatic rock formations that guide swimmers through the open sea are the high peaks of a drowned coastal landscape. During the last glacial period, between 85,000 and 15,000 years ago, the entire archipelago was a mountain range physically connected to the South American continent. As the ice sheets receded and global sea levels rose, the low-lying plains vanished underwater, leaving only these summits isolated far offshore. Today, the archipelago encompasses five main islands, four unnamed islets, five rocky slabs, and two placers, bordered by underwater drop-offs that plunge to depths of fifty metres. Swimming alongside these vertical walls, you look down through deep blue water where stone faces disappear into the ocean floor. The dominant visual marker is the main island’s central peak, which soars 316 metres above the waves and bears an unmistakable resemblance to Rio de Janeiro's Sugarloaf Mountain, serving as a massive natural beacon for swimmers navigating offshore.

The marine reserve waters around the Alcatrazes archipelago

Because these islands remained isolated for thousands of years, the archipelago evolved a pristine habitat often called the Brazilian Galápagos due to its wealth of endemic species. The protected marine reserve sustains between 200 and 250 species of fish. This biological variety surpasses even that of the celebrated Fernando de Noronha archipelago. Swimmers entering these offshore waters find themselves surrounded by a flourishing underwater world. Throughout the deeper passages, marine life can be spotted and admired.

Saco do Funil and the towering frigatebird nesting cliffs

European navigators first recorded the archipelago when an expedition led by Pero Lopes de Souza sailed past in 1530. The islands derived their name from the brown booby, a seabird known as the alcatraz, a word of Arabic origin meaning 'the diver'. The archipelago shelters the largest nesting cluster of frigatebirds in the entire South Atlantic, home to approximately 6,000 individuals. The race finishes in Saco do Funil, a sheltered cove nestled between the northern and eastern arms of the main island. Protected by steep rock faces, its transparent water provides a serene and rewarding conclusion to an unforgettable offshore swim.