Guanabara Bay boat tour: the story you sail through

Every Guanabara Bay boat tour sails over a famous mistake in Brazilian geography. A traveler's guide to the city, first written by Ramiz Galvão and republished by the National Library of Brazil, records that the bay was discovered on 1 January 1502 by the Portuguese navigator André Gonçalves.¹ Seeing the narrow entrance and the wide water behind it, he took it for the mouth of a river.

That is how the city got its name. The same guide says that Gonçalves took the bay for a river and so gave it the name it still carries, Rio de Janeiro, the River of January.² There is no great river here, only the bay, fed by small streams from the hills. Yet the name stuck, first to the settlement on its shore and finally to the whole state around it, a name now known far beyond Brazil.

The people who lived here first had their own name. The guide notes that the native inhabitants called the bay Ganabara, which others write Guanabara.⁷ That older word survived alongside the Portuguese one and is the name the bay carries on every map today. When you sail out of Marina da Glória, you are crossing water that was named twice, once by its own people and once by sailors who misread it.

The entrance to the bay was the key to the colony, and it bristled with forts. On the Niterói side stands the Santa Cruz da Barra fortress, which IPHAN says began to rise in 1578 as the main defense of the city of Rio de Janeiro.⁹ Riotur, the city tourism authority, dates its hand-cut stone walls to 1555.¹⁵ Both are official sources, so we give both dates and let the stones speak for themselves.

IPHAN credits the fortress with standing firm through the Dutch wars, between 1599 and 1663, and through the French attacks led by Duclerc in 1710 and Duguay-Trouin in 1711.¹⁶ In the early 18th century it became the largest fortress in Portuguese America.²³ Its artillery collection runs from 17th-century cannons to coastal guns that were still in use until 1998, an open-air museum of military history.²⁴

The fort never lost its job. IPHAN notes that until the 1950s every visitor who reached Brazil by ship passed under the watch of its garrison, and the Brazilian Army still uses it today, running its own visitor program.^22,25 In a recent decision the institute listed the whole group of forts at the entrance, Santa Cruz, Praia de Fora and Imbuhy, together with the hills and beaches that form the landscape of the bay mouth.²⁶

The last century added landmarks of its own, built on a scale the colonists could not have imagined. The Rio-Niterói Bridge opened on 4 March 1974, according to ANTT, the federal land transport agency.¹⁰ It runs for 13.29 km, 8.83 km of them over the water, and its central steel span stands 72 meters above the sea so that large ships can pass beneath.^19,48 Today about 150,000 vehicles cross it every day.⁴⁹

On the Rio shore, Santos Dumont Airport sits in the heart of the city, with domestic flights taking off over the bay.²⁷ Beside it, Marina da Glória, where the sunset sail begins, hosted the sailing events of the 2007 Pan American Games and the 2016 Olympic Games, according to Riotur.²⁰ The bay that once tested Portuguese caravels became a racecourse for Olympic crews from around the world.

Across the water, Niterói added a modern icon of its own. Oscar Niemeyer's Niterói Museum of Contemporary Art opened its doors on 2 September 1996, on the Boa Viagem headland.¹⁴ The city says more than 3.5 million people have visited it since then.⁵⁰ From the bay, the building and the old chapel on the island below it share a single frame, centuries apart and only a few hundred steps away from each other.

The bay is a working, urban body of water, and its wildlife lives alongside ports, ferries and a city of millions. Frigatebirds are the easiest to spot. Federal conservation scientists at ICMBio report that the frigatebirds nesting on the Cagarras islands commute across open water to fish in Guanabara Bay and head back to their islands as evening falls.⁴⁵ On a sunset sail you may see them gliding overhead, heading back out to sea.

The same agency is frank about the water. It notes that the Cagarras islands, outside the bay, are also affected by polluted water flowing out of Guanabara Bay.⁵² That is an honest reminder that decades of growth around the bay have left their mark. A swim stop near the bay mouth, where the water exchanges with the open sea, is a different matter from the inner bay near the port, and the crew decides where and whether to swim.

If wildlife is the main reason for your trip, the open sea beyond the bay offers more. Boats to the Cagarras and the Tijuca islands look for turtles, dolphins and seabirds.³⁴ From June to November humpback whales breed in Brazilian waters.⁵³ Those trips are covered in our guide to other boat trips from Rio. Inside the bay, enjoy the birds, the light and the history, which this water offers in abundance.