IMAGINE a festival with spotless toilets, a hugely diverse line-up, one venue in a cave and only 2,000 people. It never gets dark, so bedtimes are irrelevant, and for anyone needing some quiet time for contemplation, peaceful hills and beaches abound.

While this might sound like something dreamed up by a marketing executive keen to punt lager or mobile phones, such an event really exists, albeit several hours by boat from the Norwegian mainland.

Founded in 2003, the Trna Festival takes place in July on the islands of Husy and Sanna, which form part of the archipelago from which the event takes its name. Almost every Norwegian act worth hearing has played there, and it has also developed a reputation among discerning international stars who this year included Richard Hawley, Damien Rice and Swedish hip-hop outfit Looptroop Rockers.

The main festival site is on Husy’s football pitch and features an open air main stage and a dance tent among its seven venues, and, in a nod to the islands’ long-standing fishing traditions, the Fishy Fishy Nam Nam restaurant. In the background stand the jagged gneiss mountains of Sanna, home to the Kirkehelleren (“Cathedral Cave”), which was first inhabited between 6,000 and 10,000 years ago.

In 2005, the band Adjagas played in the cave and this year return to the festival having toured the world. This time their show is confined to a tent, but their enticing blend of traditional Sammi music from the north of Norway, with banjo, slide guitar and trumpet, remains a massive hit with the crowd.

In a sign of Trna’s vast musical range, which includes reggae, folk, rock and electronica acts, Adjagas are followed by Looptroop Rockers, veterans of the European festival scene.

“It looked beautiful so we wanted to come,” says frontman Promoe, whose pre-gig preparation involved kayaking to Sanna. “I’ve never seen a place like this before.”

Other Norwegian highlights include the Valkyrien Allstars playing eight-string Norwegian violins and Ingrid Olava, who performed a dazzling set in Husy’s beautiful wooden church. It boasts some rather exotic dcor, including a model sailing ship hanging from the ceiling and incongruous golden chandeliers.

Later that day, Olava is plucked from the audience to accompany Damien Rice in the Kirkehelleren. Rice’s appearance at the festival led to Chris Woolderink making the journey from Edinburgh. “After two days of walking round the festival you know nearly everyone,” he says. “There is a good mixture of both older and younger people.”

When the festival site closes at 3am, many who do not want to sleep head to a large caravan nearby which does a mean line in rave tunes. Its hosts have christened their unofficial club Camp Trollkt and its fame has spread so far that the singer of one band is spotted wearing a T-shirt bearing its name.

Elsewhere on the island, parties take place in accommodation billeting the dozens of volunteers who help run the festival. Some sleep in the local school, while others crash on mattresses in a hut with no running water. They begin the day with a morning bath in a cove where otters make an occasional appearance and seagulls pluck fish from the sea instead of feasting on discarded rubbish.

Thanks to Trna’s proximity to the Arctic Circle, it remains light for 24 hours during the festival, although the sun does set for about two hours from about 12:15am.

Knowing the time is important on Trna, not least because the one shop in town is only allowed to sell beer until 8pm. At the festival site a beer costs three “bongs” (tokens), which converts to about 6. Despite the name of the currency and a former sponsor called Green Reefers (a frozen food packing company), there is no evidence of illicit substances being consumed. However, with spirits only available from state alcohol vendors on the mainland, large plastic containers of moonshine make regular appearances.

Numerous punters take the boat to Sanna to visit the 700m-long “Love Tunnel” which leads to a Nato listening post at the top of the mountain. During the festival the tunnel is lit by candles and a violinist plays Eastern melodies in the near-darkness.

From the mountain top, the Svartisen glacier on the Norwegian mainland is visible. An extremely steep path leads back down to the Kirkehelleren, where Kings Of Convenience play a joyous acoustic set which includes frontman Erlend ye dancing around the cave like a ginger Jarvis Cocker.

“At this festival they use the names of bands to get people to go on an adventure, to go and see something they would not otherwise see,” he says. “I’m very happy to be used in this way.”

Richard Hawley is also enthusiastic about his Trna experience. He tells me he used the trip to recover from weeks in the studio and to finish off a couple of songs, before delivering an acoustic set which begins in broad daylight at 11:30pm.

“British festivals seem to be about lots of people paying for the privilege of being trapped in a field and marketed to,” he says. “I know [Trna] is sponsored by this, that and the other, but it doesn’t have that feeling of corporate sponsorship.”

With tickets and accommodation both limited and a journey to the site that takes hours, it hard to imagine this will change soon.

&#149 The Trna Festival takes place in the second week of July. For details see www.trena.net