Water pollution is just one of several dangers Singapore's sailors will face when they compete at next month's Olympic Games in Rio.
With pictures of floating rubbish and dead animals in the city's Guanabara Bay published in the media and athletes becoming victims of armed robberies, safety and security are major issues before the Aug 5-21 event.
Nacra 17 duo Justin Liu and Denise Lim have been in Brazil for more than a month to train and acclimatise and while they have not experienced any trouble, they are taking precautions.
Their rented apartment on Rua Assis Bueno is a short taxi ride away from the two sailing clubs (Marina de Gloria and Iate Clube) they are training at, but the sailors have opted to rely exclusively on Uber instead.
They even refrain from wearing sunglasses and watches to avoid attracting any unwanted attention, said the 25-year-old Lim.
Last month, Australian sailor and wheelchair basketball player Liesl Tesch and her trainer were robbed at gunpoint near Flamengo beach - which faces the bay - and three members of Spain's sailing team were mugged in April.
The water still looks blackish, so we take precautions by taking preventive medication, and ensure that we wash our hands before eating.
DENISE LIM, Singapore Nacra 17 sailor, on combating the threat of pollution at the sailing competition venue.
About 85,000 police and security personnel have been deployed around the city by the Brazilian government.
Nevertheless, Laser sailor Colin Cheng took no chances during his 21/2 week stint in Rio earlier this month. He said: "I don't carry any valuables with me when I go out; all I bring is a bit of cash, keys and my training gear.
"I didn't even bring my phone and wallet out."
The 26-year-old had stayed a 10-minute walk from competition venue Marina de Gloria. He was usually accompanied by his "tall and big-sized Australian" coach Brett Beyer.
Cheng said: "Security guards were also patrolling the bicycle paths outside the sailing club; I think those measures were put into place after the robberies."
Apart from the issues with the sewage floating on the waters, it was the unpredictable currents of Guanabara Bay that preoccupied the multiple Asian Games medallist's thoughts.
"It's a very difficult venue to read... the winds are quite light, which makes it tricky because I get more consistent results in stormier winds," said Cheng, who finished 15th overall at the London Olympics, the highest-placed Asian.
"Now that we know how different the conditions are, we know what to focus on and can sort of imagine how it'll play out."
RS:X windsurfer Audrey Yong had few complaints about the surroundings after three weeks in Rio.
The 21-year-old, who is part of the Republic's 10-strong sailing contingent across six classes, said: "The pollution is better now, the water has much less debris in it where we sail and on good days the water is a lovely clear blue."
But the sailors are following the advice of the Singapore Sports Institute doctors by taking antibiotics for the duration of their exposure to water, as well as bathing in anti-bacterial body wash daily during the Olympics.
Lim, a nurse at Changi General Hospital's accident and emergency department, said: "The water still looks blackish, so we take precautions by taking preventive medication, and ensure that we wash our hands before eating."