The final numbers won't be in for at least a couple weeks, but organizers of the fourth annual World's Largest Swimming Lesson™ expect that Tuesday's global event attracted a world record 35,000 participants at more than 700 locations in more than a dozen countries. (In 2012, WLSL set a new world record with 24,873 participants.) The event coordinates a simultaneous half-hour session, overseen by Guinness World Records, to raise drowning awareness and the importance of basic swimming skills.

"The World's Largest Swimming Lesson is a great way to send the message swimming lessons save lives," said Janet Evans, four-time Olympic gold medalist, who joined 800-plus swimmers and fellow Olympic gold medalist Misty Hyman at Big Surf Waterpark in Tempe, Ariz., in an attempt to beat the previous Guinness World Record (set in 2011) of 611 participants for the single largest WLSL location.

Drowning remains the second leading cause of accidental death for kids ages 1 to 14 and the leading cause of accidental death for kids 1 to 5. Research shows participation in formal swimming lessons can reduce the risk of drowning by 88 percent among children under 4 years old.

"A lot of it is safety skills ... and there's also some basic skills like blowing bubbles, submerging your face ... mostly just to get awareness out about it and to help the parents know the kinds of things that their kids should know to be safe in a pool area," Emily Decker, the learn to swim director at Civic Center Water Park in Mentor, Ohio, told The News-Herald of Willoughby.

The WLSL at Bethesda (Md.) Country Club was organized by a mother whose son almost died in a pool accident. "He fell in the deep end," Laura Metro told the ABC-TV affiliate in Arlington, Va. "He was in a coma for two days. We didn't know if he would live or die. We didn't know if, when he woke up, he would have brain damage, and he made nothing short of a miraculous recovery." Metro has since founded the C.L.A.Y. Foundation, a non-profit organization that advocates for swim instruction, CPR training, and AED availability.

Here's how (and why) some facilities celebrated the day:

Bethesda (Md.) Country Club

Civic Center Waterpark, Mentor, Ohio

Norm Waitt Sr. YMCA, South Sioux City, Neb.