RIO DE JANEIRO — Ian Andrewes, a coach for the Canadian sailing team, thought he had seen every type of flotsam and jetsam in his years on the water.

That was until he and his team began training for the Rio Olympics here two years ago.

Heading out to the Atlantic Ocean from Guanabara Bay, he spotted a Brazilian navy ship in the distance performing a burial at sea.

And, with just days to go before the start of the Games, the amount of debris in the water is “getting worse, not better,” Andrewes said.

The pollution overwhelming Guanabara Bay has raised significant concerns about the health of the swimmers and sailors who will compete in the bay’s water at the Rio Olympics. Organizers have said they have swept a lot of the debris from the water where the competitions will be held, but cannot answer for the rest of the bay. They also said that they had done enough bioremediation to stem the waste that fouls the expansive bay and its famous ocean beaches.