"Everyone is so upbeat, and everything seems so well regulated," Sacco said.

The mood was happy during the early part of yesterday afternoon, when the weather was sunny and temperatures averaged about 70.

"There was tremendous turnout and the people were very friendly," said David C. Gordon '96, a member of Harvard's lightweight men's crew. "Just to participate with 200,000 people watching is an incredible and unique experience."

Gordon said the crowds reduced the pressure on those competing in the regatta.

"It's more festive," Gordon said. "It's not as serious and you also have a good time."

Many families and students spread out blankets and had picnics near the river. Spectators said they found a more festive atmosphere than at many other athletic events.

"People come together here," said Melissa Brown, a sophomore at Stone-hill College in North Easton, Mass. "It's really a competition. Everyone is really laid back."

But the supporters of U.S. Senate candidates had to work. They displayed signs and set up booth to spread the word about U.S. Sen. Edward M. Kennedy '54-'56 and his challenger, Belmont entrepreneur W. Mitt Romney.

The afternoon ended damply. Around 4 p.m. in the afternoon, the same time major races started, it began to rain. Traffic congestion and panic were the immediate results of the downpour, as cars poured out of a newly sodden Cambridge