Interest in aquatics appears to be on the rise, according to an annual survey from the National Sporting Goods Association.

The closely watched survey found swimming was the No. 2 most popular sport activity in 2008. With 63.5 million participants, it jumped 6.1 percent over 2007 — the first time in the survey’s 25-year history that swimming has shown more than a year-to-year increase.

Since 1990, exercise walking has been the No. 1 activity. In 2008, swimming moved ahead of No. 3, exercising with equipment, which had 63 million participants.

Swimming is always among the top sport activities surveyed, said Larry Weindruch, NSGA director of communications. However, results from the past 25 years shows a general decrease in participation.

“We started surveying swimming in 1984, and that was the highest number of participants. We registered, 74.4 million that year,” Weindruch noted. “2003 was the lowest, with 47 million.”

Experts say it’s too early to call it a bona fide trend, but swimming participation is growing again. Except for a drop in 2006, survey results show participation has increased each year since 2003.

Bruce Wigo, CEO of the International Swimming Hall of Fame in Fort Lauderdale, Fla., is optimistic the increases of the past several years will continue as the industry develops more modern pools with amenities to accommodate all types of people.

“I think we might be on the verge of a new golden age of swimming,” he said.

Weindruch said that while it’s difficult to explain year-to-year changes, one reason for the recent upswing might be that aging baby boomers are looking for healthy activities that don’t put a lot of stress on joints and muscles.

The “staycation” trend and the focus on Michael Phelps at the 2008 Summer Olympics also likely spurred participation last year.

The NSGA survey, a written questionnaire, was conducted by the Westbury, N.Y., office of

research firm IPSOS. It included approximately 10,000 households. Respondents were not asked how many times they swam or whether they did so recreationally or competitively.