|Location||Rio de Janeiro, Brazil|
|Coordinates||22°47′25″S43°9′20″W / 22.79028°S 43.15556°W Coordinates: 22°47′25″S43°9′20″W / 22.79028°S 43.15556°W|
|Native name||Baía de Guanabara (Portuguese)|
|Ocean/sea sources||South Atlantic|
|Max. length||31 km (19 mi)|
|Max. width||28 km (17 mi)|
|Surface area||412 km2 (159 sq mi)|
|Islands||Ilha do Governador, Ilha de Paquetá, Freguesia|
|Settlements||Rio de Janeiro, Niterói, Duque de Caxias, São Gonçalo|
Guanabara Bay (Portuguese : Baía de Guanabara, [ɡwɐ̃nɐˈbaɾɐ] ) is an oceanic bay located in Southeast Brazil in the state of Rio de Janeiro. On its western shore lie the cities of Rio de Janeiro and Duque de Caxias, and on its eastern shore the cities of Niterói and São Gonçalo. Four other municipalities surround the bay's shores. Guanabara Bay is the second largest bay in area in Brazil (after the All Saints' Bay), at 412 square kilometres (159 sq mi), with a perimeter of 143 kilometres (89 mi).
Guanabara Bay is 31 kilometres (19 mi) long and 28 kilometres (17 mi) wide at its maximum. Its 1.5 kilometres (0.93 mi) wide mouth is flanked at the eastern tip by the Pico do Papagaio (Parrot's Peak) and the western tip by Pão de Açúcar (Sugar Loaf).
The name Guanabara comes from the Tupi language, goanã-pará, from gwa "bay", plus nã "similar to" and ba'ra "sea". Traditionally, it is also translated as "the bosom of sea".
Guanabara Bay was first encountered by Europeans on January 1, 1502, when one of the Portuguese explorers Gaspar de Lemos and Gonçalo Coelho  arrived on its shores. According to some historians,  the name given by the exploration team to the bay was originally Ria de Janeiro "January's Lagoon", then a confusion took place between the word ria "lagoon" and rio "river". As a result, the name of the bay was soon fixed as Rio de Janeiro. Later, the city was named after the bay. Natives of the Tamoio and Tupiniquim tribes inhabited the shores of the bay.
After the initial arrival of the Portuguese, no significant European settlements were established until French colonists and soldiers, under the Huguenot Admiral Nicolas Durand de Villegaignon invaded the region in 1555 to establish the France Antarctique. They stayed briefly on Lajes Island, then moved to Serigipe Island, near the shore, where they built Fort Coligny. After they were expelled by Portuguese military expeditions in 1563, the colonial government built fortifications in several points of Guanabara Bay, rendering it almost impregnable against a naval attack from the sea. They were the Santa Cruz, São João, Lajes and Villegaignon forts, forming a fearsome crossfire rectangle of big naval guns. Other islands were adapted by the Navy to host naval storehouses, hospitals, drydocks, oil reservoirs and the National Naval Academy.
Underwater exploration in the bay was disallowed by the Brazilian government in 1985 amid a dispute with an American treasure hunter, who claimed to have found evidence of a Roman shipwreck. 
There are more than 130 islands dotting the bay, including:
The bay is crossed by the Rio-Niterói Bridge (13.29 kilometres (8.26 mi) long and with a central span 72 metres (236 ft) high) and there is heavy boat and ship traffic, including regular ferryboat lines. The Port of Rio de Janeiro, as well as the city's two airports, Galeão - Antônio Carlos Jobim International Airport (on Governador Island) and Santos Dumont Airport (on reclaimed land next to downtown Rio), are located on its shores. The Federal University of Rio de Janeiro main campus is located on the artificial Fundão Island. A maze of smaller bridges interconnect the two largest islands, Fundão and Governador, to the mainland.
There is an Environmental Protection Area (APA), which is located mostly in the municipality of Guapimirim and given the name of Guapimirim APA.
Guanabara Bay's once rich and diversified ecosystem has suffered extensive damage in recent decades, particularly along its mangrove areas.  The bay has been heavily impacted by urbanization, deforestation, and pollution of its waters with sewage, garbage, and oil spills. As of 2014, more than 70% of the sewage from 12 million inhabitants of Rio de Janeiro now flows into the bay untreated. 
There have been three major oil spills in Guanabara Bay. The most recent was in 2000 when a leaking Petrobras underwater pipeline released 1,300,000 litres (340,000 US gal) of oil into the bay, destroying large swaths of the mangrove ecosystem. Recovery measures are currently[ when? ] being attempted, but more than a decade after the incident, the mangrove areas have not returned to life.[ needs update ]
One of the world's largest landfills is located at Jardim Gramacho adjacent to Guanabara Bay. It was closed in 2012 after 34 years of operation. The landfill attracted attention from environmentalists and it supported 1700 people scavenging for recyclable materials. 
In June 2014 Dutch windsurfer and former Olympic and world champion Dorian van Rijsselberghe made an urgent appeal to government and industry in the Netherlands to collaborate in cleaning up the bay, together with the Plastic Soup Foundation.   The Dutch government picked up the message and formulated a Clean Urban Delta Initiative Rio de Janeiro together with a consortium of Dutch industry, knowledge institutes and NGOs which will be presented to the Brazilian authorities in the State of Rio de Janeiro.
As part of the preparations for the 2016 Summer Olympics in Rio, the government was supposed to improve the conditions, but progress has been slow. There have been concerns that the efforts may only be short-term and abandoned following the Games, as there would be little political incentive to continue with them. 
The marine ecosystem of Guanabara Bay was severely damaged;  the bay was once a whaling ground,    and today whales are no longer or rarely seen while Bryde's whales can be seen around the bay entrance.     The bay is also home to a population of botos   and this population faces severe risks of population decline. 
Mem de Sá was a Governor-General of the Portuguese colony of Brazil from 1557 to 1572. He was born in Coimbra, Kingdom of Portugal, around 1500, the year of discovery of Brazil by a naval fleet commanded by Pedro Álvares Cabral.
Governador Island is the largest island in Guanabara Bay, in Rio de Janeiro, Brazil. It has a population of about 211,018 inhabitants, in a small area of 42 km2 (16 sq mi).
The Brazilian Naval Revolts, or the Revoltas da Armada, were armed mutinies promoted mainly by admirals Custódio José de Melo and Saldanha da Gama and their fleet of rebel Brazilian navy ships against the claimed unconstitutional staying in power of president Floriano Peixoto.
Ilha Grande is an island located off the coast of Rio de Janeiro state, Brazil. The island, which is part of the municipality of Angra dos Reis, remains largely undeveloped. For almost a century it was closed by the Brazilian government to free movement or settlement because it first housed a leper colony and later a top-security prison. The Cândido Mendes prison, which housed some of the most dangerous prisoners within the Brazilian penal system, was finally closed in 1994. The largest village on the island is called Vila do Abraão with approximately 1900 inhabitants.
Villegagnon Island is located near the mouth of the large Guanabara Bay, in the city of Rio de Janeiro, Brazil.
Galeão may refer to:
Guapimirim Environmental Protection Area is a coastal marine protected area on Guanabara Bay in the state of Rio de Janeiro, southeastern Brazil.
Several years after the Portuguese first explored Brazil, French traders in search of pau-brasil reached the rich area extending from the Cape Frio coast to the beaches and islands of Guanabara Bay, the economic and, above all, strategic importance of which was already well-known.
The Grêmio Recreativo Escola de Samba União da Ilha do Governador was founded on March 7, 1953 by the friends Maurício Gazelle, and Quincas Orphylo, who were in Cacuia, the main site of the carnival parade of the Ilha do Governador, watching the presentation of small schools of samba and blocks of various districts of the island. It was then decided that the neighborhood of Cacuia should be represented by a samba school. Currently, the school is based in Estrada do Galeão in the neighborhood of Cacuia.
Ilha das Cobras is an island located within Guanabara Bay in the city and state of Rio de Janeiro, Brazil. It is east of the neighborhood Guanabara. It is home to the Arsenal de Marinha do Rio de Janeiro base of the Brazilian Navy.
Ilha Fiscal, or Fiscal Island, is an island in Guanabara Bay, bordering the historic city center of Rio de Janeiro, in southeastern Brazil.
The Port of Rio de Janeiro is a seaport in the city of Rio de Janeiro, Brazil located in a cove on the west shore of Guanabara Bay. It is the third-busiest port in Brazil, and it is managed by Companhia Docas do Rio de Janeiro.
The Ilha Anchieta State Park is a state park in the state of São Paulo, Brazil
The Central Rio de Janeiro Atlantic Forest Mosaic (Portuguese: Mosaico da Mata Atlântica Central Fluminense is a protected area mosaic in the state of Rio de Janeiro, Brazil. The mosaic is inland, to the east of the city of Rio de Janeiro.
The Guanabara Ecological Station is an ecological station in the state of Rio de Janeiro, Brazil. It protects an area of mangroves in Guanabara Bay, not far from the city of Rio de Janeiro.
The Bacia do Rio Macacu Environmental Protection Area is an environmental protection area in the state of Rio de Janeiro, Brazil.
The Ilha do Cardoso State Park is a state park on the coast of the state of São Paulo, Brazil. It preserves a large area of Atlantic Forest on the Ilha do Cardoso, an island, and includes marshes and mangroves that form an important breeding area for marine life. Visitors may reach the island by boat and stay in one of the villages. They may visit the beaches or follow trails into the interior, where there are waterfalls and natural pools.
Forte de São Lourenço is a fort located in Itaparica, Bahia in Brazil. It sits on a strategic point at the north of Itaparica Island on a site used for whaling in the early 17th century. The Dutch constructed a small earthwork fortification on the site during the Dutch occupation of Brazil (1630–1654); it was reconstructed by the Portuguese in its present form in the early 18th century. The fort was used by Brazilian forces during the Brazilian struggle for independence in 1823; the Brazilian Navy has owned the fort since the same year. The Forte de São Lourenço was listed as a federal historic structure in 1938.
Rio de Janeiro is on the far western part of a strip of Brazil's Atlantic coast, close to the Tropic of Capricorn, where the shoreline is oriented east–west. Facing largely south, the city was founded on an inlet of this stretch of the coast, Guanabara Bay, and its entrance is marked by a point of land called Sugar Loaf – a "calling card" of the city.
The Ilha Grande mangroves ecoregion covers a series of disconnected salt-water and brackish mangrove forests along the southeastern coast of Brazil on the South Atlantic Ocean. The ecoregion is defined as covering the mangroves found between the Paraíba do Sul River in the north to Florianópolis in the south. This coastal region is the most densely population region of Brazil, and many of the mangroves are in close proximity to ports and industrial cities. A number of ecological reserves have been established to protect the high biodiversity of the mangroves, recognizing their importance to migratory birds, and as nursery habitat for juvenile fish, crabs, shrimp, and mollusks.
Media related to
Guanabara Bay at Wikimedia Commons