"We almost think of it as land," said Carrie Howe, a member of the U.S. team and her three-person squad's unofficial algae remover. During practice, she dips her hand into the goo three or four times an hour to remove it from the rudder.
When it collects shaggily on the boat's tow rope, she and her teammates refer to it as "the dog." They've named it Hickory.
Chinese officials are trying to make the stuff go away. Hundreds of soldiers cleaned it up by hand in a seaside park Wednesday. About 10,000 ordinary citizens were doing the same along the shore, while more than 1,200 fishing and other boats hauled it in by net, the workers smiling and flashing the two-fingered victory sign to journalists.
"We all need to pitch in," said Gao Shaofan, a massage parlor employee who was stuffing the algae into plastic sacks with her co-workers. "This is the worst it's ever been that we know."
Chinese officials promised at a news conference Wednesday that the Olympics competition area, all 19 square miles of it, will be clear of the algae before races begin Aug. 9.
"Actually, we don't have a backup," Qu Chun, the sailing competition manager, said to a small chorus of groans from coaches.
The sailing teams had already known Qingdao, a charming port on China's east coast known for its Tsingtao beer, would be a difficult venue. The lower-than-ideal winds. The stronger-than-ideal current. The soupy fog that sometimes keeps teams off the water.
Then came the algae, which one Chinese official at the news conference, Lu Zhenyu, called a "natural disaster." First detected in May, it recently swelled to stretches of up to a few miles long.
Chinese officials and some experts blamed it on a combination of factors including warmer seas, winds from the south and an "exotic" strain of algae from farther down the coast.
You could eat it if you want, they added, saying Japanese and Koreans do.
"In itself, it's not harmful," said Fei Xiugang, who described himself at the news conference as a seaweed expert. "It absorbs carbon dioxide. It actually cleans the water."
But Wang Liqing, a marine biology professor at Shanghai Ocean University, said in a phone interview that the bloom could be caused by pollution, which deposits excessive nutrients in the water and causes algae to grow at abnormal rates. China's east coast is highly industrial.
Whatever the cause of the algae, the sailors — who didn't become Olympians through negative thinking — have tried to describe it in not-so-terrible terms.
"A very new, very large variable," Howe said.
"Oh my goodness," said Karyn Gojnich of the Australian team.
"A green nightmare," said Andreas Kosuratopoulos of the Greek team, dropping the Olympian guard.
"We've watched the Dutch Yngling team, coach boat and three boats in tow get stuck so badly they had to be hooked and hauled out by a local fishing trawler," U.S. sailor Andrew Campbell wrote in his blog last week.
Scattered patches of the algae were beginning to stink, some sailors said.
The 30 or so Olympic teams already training at Qingdao are preparing for the possibility that the algae won't be gone before the games. "Everyone's a bit skeptical about how they will get it done," Howe said.
Chinese officials have appealed to Qingdao's civic pride — and fishermen's wallets — to fight the algae bloom as quickly as possible, with the goal of clearing the competition zone by July 15.
Already, 170 tons have been cleared away, said Zang Aimin, an executive board member of the Beijing Organizing Committee for the Olympic Games.
"As far as protecting the competition area, I'm confident we can do it," she said, adding that Navy dredging boats were on the way.
Gojnich was impressed by the response of Chinese fishing boats. "It's like being surrounded by the Spanish Armada," she said. But some athletes and coaches say the algae seems to keep coming back.
Chinese officials promise a system of nets to hold the roaming algae back from the Olympics sailing area, as well as daily briefings on the cleanup effort. They also hope winds from the north will blow the algae away, and soon.
Eager to show off their efforts, officials took journalists on a barge Wednesday afternoon to watch a massive pumping system suck up swathes of Qingdao's bright green headache, plowing through the tide like a vacuum cleaner.
"This has nothing to do with bad luck," said Wang Zhijun, head of Qingdao's harbor administration office, as he watched the pump, smiling for the cameras. "This is just nature."
Back on shore, a group of Chinese swimmers, most of them retirees, jumped into the harbor and ignored the bits of algae that clung to their naked backs.
"Well, it's not poison," said Zhong Pihua, teasing. "Come on in."