Rio de Janeiro's Olympic bid included a promise to clean up the filthy waters of Guanabara Bay, venue for sailing events during Rio 2016. However, with less than two-and-a-half years to the start of the games, the water is contaminated with dangerous levels of raw sewage, and its beaches are littered with rubbish.

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A man walks past rubbish on Botafogo beach, with Sugar Loaf Mountain in the background

City authorities had planned to treat 80% of Rio's sewage, but Gelson Serva, Deputy State Secretary of Environment says only 34% of its human waste is treated - the rest goes into the bay.

There are more than eight million people in the 15 cities surrounding Guanabara Bay, producing over 18,000 litres of sewage per second. Leona Deckelbaum of the NGO, My Rio, told the BBC the level of faecal matter in the bay is 198-times higher than the US legal limit. "I wouldn't put my little pinky toe in it," she said.

There are fears that the water is unsafe for swimming and will be too polluted to host Olympic events.

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A toilet seat is seen on Galeao beach, and a tyre is pictured near a fishing boat off Fundao beach
Boats float along the shoreline of the polluted waters of Guanabara Bay
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In March 2013, more than 65 tonnes of dead fish covered the surface of the Rodrigo de Freitas lagoon, Rio de Janeiro's Olympic rowing venue
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Municipal workers spent two days clearing the dead fish from the lagoon after rotting plant life caused oxygen levels in the water to drop
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Plastic toys litter a beach on Pombeba island in Guanabara Bay in Rio de Janeiro
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A sewage outlet is seen on Galeao beach in Rio de Janeiro
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A cable car travels over the Alemao favela in Rio. Brazil is approaching 90% urbanisation, as its citizens flock to cities
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Old boats are reflected in the polluted waters of Guanabara Bay
Children play in the polluted waters of Guanabara Bay in the Ilha do Governador neighbourhood of Rio
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Rubbish is strewn on a beach near a fishing boat in Guanabara Bay
A polluted stream that runs into Guanabara Bay is seen in Duque de Caxias, north of Rio de Janeiro
A child's broken doll lies washed up on Fundao beach on Rio de Janeiro's Guanabara Bay