HONOLULU — When Roy Sakuma first rounded up ukulele players for a festival at a Waikiki Park, he gathered 50 musicians and had an audience of 100.
This year, some four decades later, 900 people strummed and plucked their wooden four-string instruments in front of several thousand people lounging on benches and under tents on a sunny day at Kapiolani Park.
"That sweetness and charm of this instrument, just attracts you," said Mr. Sakuma, on the sidelines of the 41st annual Ukulele Festival on Sunday.
The players ranged from novice five-year-olds attending Mr. Sakuma's ukulele schools on Oahu to stars like Jake Shimabukuro, who first performed at the event as a child decades ago.
The musicians were also international, including artists from Thailand, Italy, South Korea and the U.S. mainland.
Mr. Sakuma said many people have long failed to take the ukulele seriously because they thought it was a toy. But he said that's changing as more people encounter it.
Novelty singer Tiny Tim introduced many in America to the ukulele in the late 1960s and early 1970s. Now, mainstream artists, like Eddie Vedder, the lead singer of the band Pearl Jam, have taken up it up. Mr. Vedder has recently been on tour to promote his solo album, "Ukulele Songs."
Mr. Shimabukuro, who is in Hawaii only briefly between U.S. mainland and Japanese tours, said Internet sites like the video-sharing service YouTube are helping spread the popularity of the ukulele.
"It's so easy to watch and copy, and you can learn right away," he said.
He also attributes the instrument's appeal to its sound, which he said resembles children laughing.
"When people hear that it makes them feel young, it makes them feel like a kid," he said. "That's wonderful because it brings a different type of joy to you, and that joy is infectious."