As the sun shimmered yellow then sank past the horizon, nearly 1,000 people packing the hot Costa Rican beach paused their drum beating and hoop dancing to cheer like pagans.
The moment, captured on cellphones and a hovering drone, is part of Envision: an annual four-day festival that has grown exponentially over 10 years from a small gathering of party-minded Americans into a big international event.
Hosted on a coastal property, it sees more than 5,000 skimpily clad ticket holders diving into electronica beats, yoga classes, art, concerts, healthy food and spiritual precepts.
It's a millennial gathering, with mostly North Americans flying down to escape their winter for a long weekend camping party on a tropical beach. That means MacBooks among the marijuana, vegans not adverse to vodka shots, and selfies on the sand.
Entry isn't cheap -- tickets run from $300 for a pass and a camping spot up to $3,000 for a VIP treehouse experience, not including airfare.
But the three dance areas are deliriously decked out, one featuring mini-towers shooting flames to the beat, and security, both private and police, is plentiful.
For the festival goers, it's a safe tropical dance party that doesn't skimp on the technology: There's internet, credit card machines at bars, and in-house pro video teams with the latest gear -- drones included -- feeding it all to Facebook.
"We like to refer to it as jungle tech," Justin Brothers, one of the festival's founders and its marketing chief, told AFP.
- 'Jungle juiciness' -
Comparisons with Burning Man, a similar but far bigger and older US festival held each year in Nevada's desert, are inevitable.
Many of Envision's performers, some of its workers and quite a few of its ticket buyers also go to that event. Brothers said his festival is increasingly being seen as "the Burning Man of Central America."
But while the alternative crowd and the commercial aspects to both are obvious, some key differences set them apart, he said, starting with Costa Rica's "sweaty, hot, beachside jungle juiciness."
A couple of professional Californian fire dancers performing at Envision and walking by in fetish outfits and face markings said they found the two festivals "similar" in some ways.
But Envision had "a bit more of a hippy, family vibe," said one of them, Samantha Taylor, 34, while her mother pushed a baby in a three-wheel carriage lit up with neon lights nearby.
One festival-goer, Christopher Nadig, a 34-year-old financial advisor from the Midwest US state of Minnesota, said simply: "You have to be in the tropics for paradise."
- 'Largely American' -
James Grant, a 39-year-old American consultant living in Costa Rica and paying for the pricey VIP pass, was blunt about what drew him and his friends back for his second Envision.
"We're not into yoga and all that shit. We like drinking," he said.
Just outside the festival grounds, on the public beach, a French couple took an entrepreneurial approach to the thousands of visitors, selling $5 mojito cocktails from a cool box.
"It's all very Americanized, a bit like Burning Man," said Lea, a 32-year-old graphic designer from Paris who gave just her first name.
The organizers however are keen to broaden the festival's appeal to Latin Americans and others, and offer steep ticket discounts to encourage Costa Ricans to come.
One such local on his fourth Envision festival was Fernando Bolanes, a 37-year-old actor from the capital San Jose who slipped easily into English.
"It is largely American," he said.
But that was part of its appeal: "I love it because of the great music and also because of the people," he added.
Americans "are more extroverted than Costa Ricans and that's a nice change," he said.
One of the American volunteers at the festival, a 68-year-old retired school teacher going by the name of Maji, said the combination of the energy and music reminded him of Woodstock, the historic 1969 free-love music festival.
But, he joked: "The big difference with Woodstock is $500."