The annual three-day music and wakeboard festival, Wakestock, has begun in Cardigan Bay.
The 11th festival, which has world-standard wakeboarding contests by day and bands and DJs by night, could see up to 15,000 campers every night.
Among the line-up of bands for the event at Abersoch are Feeder, Plan B, Maximo Park, The Ting Tings.
Weather forecasters have predicted a mixture of sunshine and showers over the weekend.
Wakeboarding involves riding a short, broad water ski like a surfboard and performing tricks, including spins of up to 180 degrees, as the board is towed by a boat.
A purpose-built rail has been put up at Pwllheli marina for wakeboard riders to use to perform tricks.
Wakestock, which last year celebrated its 10th anniversary, has been hailed as one of Europe's largest wakeboard music festivals.
Last year it saw more than 35,000 descend on the location which is within sight of Snowdonia.
A spokesperson said Wakestock had grown from an event started by the festival's founder Mark Durston.
She said: "He just realised there was a connection between extreme sports and and music.
"It began as party on the headland above the yacht club with music by local bands and has just grown from there.
"This year there's a pretty good weather forecast. It looks set to be a great weekend."
Police have warned they will be cracking down on under-age drinking throughout the weekend.
Food and alcohol will be on sale inside the venue, but those who look under 21 may be asked for proof of age.
No food or drink can be taken into the site, apart from 500ml of water in a plastic container with an unbroken seal.
Television and radio coverage for this year's event includes BBC Radio 1 and S4C on Saturday and Sunday, 3 and 4 July.