Circuito MASF — Praia Vermelha (Urca)

Under the direct shadow of Sugarloaf Mountain, Praia Vermelha forms an intimate amphitheater where ocean swells vanish against towering granite walls. Here, along the coastline of Rio de Janeiro, the Circuito MASF — Praia Vermelha (Urca) stages an open water swimming race in the sheltered sea. Organized by Maratona Aquática Sem Fronteiras, a circuit connecting athletic technique with environmental purpose since 2014, the event offers swimmers an unusual encounter with the city's natural geology. Taking place in the spring month of October, the race provides three distinct course lengths designed for varying levels of open water experience: a 500-meter sprint, a middle-distance 1,250-meter test, and a complete 2,500-meter challenge. Swimmers launch directly off the sand into the bay, turning between reference buoys while sighting off the dark granite precipices that enclose the cove. The rhythm of the stroke settles quickly here, free from the rolling ocean swell that characterizes the open Atlantic beaches just around the headland.

Praia Vermelha cove: sheltered sanctuary and Pedra do Anel reefs

Praia Vermelha sits deeply tucked into an inlet at the foot of Sugarloaf Mountain. The surrounding stone spurs absorb the brunt of the Atlantic rollers, turning the water inside the cove into a placid, secure basin where swimmers can focus entirely on pacing and stroke mechanics. The cove feels secluded from the metropolis, cradled by sheer vertical walls of granite that plunge straight into the sea. Beneath the surface, this quiet pocket functions as a vibrant marine sanctuary, noted across the region for its biodiversity. Further out toward the mouth of the cove, approximately 800 meters from shore near the rock formation of Pedra do Anel, the underwater landscape reveals healthy marine life where fish, sea turtles, and encrusting corals colonize the submerged rocks.

Urca waterfront: reddish sands, Pista Cláudio Coutinho, and Mureta

The beach itself takes its name from the distinctive character of its shoreline, where sand rich in red crystals gives the beach a distinctly reddish hue. In the late afternoon, as the sun drops behind the city, the slanted light reflects against these mineral particles, making the entire beach glow with a warm terracotta sheen at the base of Sugarloaf Mountain. From the edge of the sand begins the Pista Cláudio Coutinho, a paved coastal path running 1.25 kilometers along the foot of the granite precipice directly beside the water. Flanked by vegetation clinging to the rock face, the walkway offers a shaded post-race stroll where native wildlife thrives. Small marmosets leap through the branches above, while birdwatchers frequently spot the brilliant scarlet plumage of the tiê-sangue bird flitting among the foliage.

Behind the cove lies the tranquil neighborhood of Urca, an enclave distinct from Rio's high-rise shorefronts with its quiet residential streets and low-rise architecture stamped with 1920s and 1930s Art Deco influences. At sunset, the ritual is to gather along the Mureta da Urca, a low stone wall lining the waterfront where locals sit overlooking the harbor with cold beer. Casual bars and eateries near the Mureta da Urca serve plates of grilled fresh fish and traditional savory snacks as the evening light fades across the water.

Guanabara Bay mouth: colonial corsair raids and harbor fortresses

The region carries a dramatic military legacy born of European rivalries for control of the bay. In August 1710, about five kilometers from the race area, a French privateer attempted a bold naval raid on colonial Rio de Janeiro. The Portuguese defenders resisted fiercely, thwarting the assault and capturing Duclerc along with more than 600 of his privateers. Retaliation arrived just thirteen months later, in September 1711, when a larger French squadron commanded by René Duguay-Trouin forced its way past the harbor entrance. Sailing directly through the narrow corridor between the guardian forts, the fleet took heavy defensive cannon fire, suffering 300 casualties before passing beyond the range of the coastal batteries. During the fierce engagement inside the bay, Portuguese crews ran three of their own warships aground and scuttled them to avoid capture, while a fourth ship was seized and burned by the invaders. Following the raid, the French fleet departed loaded with plunder valued at four million pounds.

Morro do Leme and Ilha de Cotunduba: bastions and nature reserve

At Praia do Leme, the coastal ridge rises steeply into Pedra do Leme, blanketed in thick Atlantic Forest. Crowning this promontory is Forte Duque de Caxias, originally erected between 1776 and 1799. Skirting the rock cliffs at the foot of the headland is the Caminho dos Pescadores, a stone path hugging the edge of the open sea that has long drawn local line fishermen watching the rollers break against the granite. Looking seaward across the channel, the rocky mass of Ilha de Cotunduba rises sharply from the ocean to a height of 73 meters. Featuring a 340-meter-long lower spur to the southeast, the island long served a utilitarian military role as a live target for heavy artillery batteries firing across the water from Fortaleza de Santa Cruz da Barra.

The surrounding passage was notoriously hazardous in poor visibility, culminating in November 1894 when the steamboat Amazonas ran aground and was wrecked against the island's cliffs during thick maritime fog. Today, that turbulent past has been replaced by strict environmental stewardship: since 1995, Cotunduba has been preserved as a protected Wildlife Conservation Zone, where all resource extraction and waste disposal are barred.