The annual Pacu Jalur race in Riau culminates on Sunday, with officials estimating as many as 100,000 more spectators this year because of 11-year-old Rayyan Arkan Dikha's dance moves on the fast-moving boats.

"I came to watch Pacu Jalur because I wanted to film and show the festival to the world," Australian tourist Duncan McNaught told AFP.

"I think the guys who row are crazy. They're awesome. I'm just looking forward to it."

A 20-second clip of Rayyan dancing on the boat has racked up millions of views on social media. 

Sports stars including Formula One's Alex Albon and MotoGP's Marc Marquez imitated his moves in their own videos, swirling their hands then swinging their arms back and forth.

The viral dance craze has drawn visitors from across the country and world to the Kuantan river in Riau Province.

Yuyun Kurnia, 38, travelled from the North Sumatran city of Medan, a 17-hour drive away, to watch Pacu Jalur after learning about it online.

"After it went viral on social media, I want to see Pacu Jalur directly," she told AFP, adding that it was "amazing" to watch the race in person.

Last year, the race drew 1.4 million visitors and more than $2.5 million to the local economy, according to the tourism ministry.

This year, 1.5 million spectators are expected, with a significant influx of foreigners, Riau tourism agency head Roni Rakhmat told AFP.

Officials believe revenue could jump to as much as $4.6 million on the back of increased per-person spending.

'Super cool' 

Pacu Jalur dates back to the 17th century, according to a local government website, when residents transported goods and people using traditional wooden long boats called "jalur".

The boat evolved to be used for races, now held every August.

Residents said they were happy the young boy's celebrity had drawn more eyes to the race.

"I think it's super cool that a kid his age managed to create a personal branding through Pacu Jalur. Through his dances, he has introduced Pacu Jalur to the entire world," 18-year-old Naysila Ayunita Sari told AFP.

The event transformed a stretch of the Kuantan river, with tents and umbrellas lining the riverbank.

Some spectators plunged into the river to get a close-up look at the race.

The boat dancer's precarious role on the front tip of the boat is meant to encourage the oarsmen.

"That kid standing and dancing on a boat, that's not easy at all," said 35-year-old resident Frima.

"If you ask me whether I'm brave enough to try... the answer is no."

'Grateful' 

More than 220 teams, mostly representing local villages or districts, took part in this year's races.

They are competing for combined prizes of around Rp 900 million ($55,000), Roni said.

Authorities are using the increased exposure to improve the event's organisation and the cleanliness of the river, according to Roni.

Police and the military were moving to stop illegal gold mining near the stretch of river before the race to reduce pollution, he said.

"Compared to previous years, there weren't any foreigners watching Pacu Jalur. Now there are," he said.

For locals like Frima, who have watched the race since childhood, the new interest in the race is beyond their imagination.

"I never would have thought that all eyes are on this small place on the western side of Riau," he said.

"I'm grateful Pacu Jalur is now known worldwide."