US Edition Bardsey, a wild scrap of land in the Irish Sea, is straight from the pages of a medieval romance. With its ragged skerries, mist-hung mountain and ancient burial sites, the island has inspired many legends. According to one, Bardsey is where Merlin sleeps away the centuries in a glass castle, imprisoned by a woman to whom he revealed his magical secrets; another says that it's Avalon, the resting place of King Arthur.
None of this is mentioned in the new King Arthur film, which is bound to stir up interest in all things Arthurian when it opens in the UK next week - but then this is a movie that has King Arthur living in Roman Britain and in which Merlin has no mystic powers. So what does it know?
In any event, there's no denying that getting to Bardsey is a quest worthy of the Round Table. First, I make my way to Llyn, a peninsula of deep-hedged lanes and smugglers' caves justly known as the Land's End of Wales. Then I follow the ancient pilgrims' route to the tiny, twisty village of Aberdaron, head west out of the village to a remote hill farm, and hike down a gorge to the hidden fishing cove of Porth Meudwy. From there a boat makes the 20-minute crossing - weather permitting, for Bardsey is surrounded by some of the most dangerous rip-tides in Europe and the island's Welsh name, Ynys Enlli, means "island of currents".
Today I'm lucky. A boat arrives at the appointed hour to collect us and our plastic-wrapped luggage. There's a lot of it: with no shops on the island, visitors must manhandle their own food, drink and supplies.
Rounding the headland we catch our first glimpse of the beast. Bardsey is not just whale-shaped; it has the profile of a cetacean in its 17th month of pregnancy. A treeless, bulging rump of mountain sheers off into grassland and rocky shore, with a lighthouse standing proud on the headland. It looks forbiddingly bleak.
But inaccessibility has worked in Bardsey's favour, deterring casual day-trippers. Welsh emotions run high over the island, which has been protected by the Bardsey Island Trust since 1979. The charity controls visitor numbers and the pace of development. From spring to early autumn the trust lets out its traditional buildings to visitors. Accommodation ranges from a whitewashed crogloft cottage to grand Victorian farmhouses. I'm in Nant, a stone-and-slate house beside the ruined 13th-century abbey, overlooking a scintillating sea.
Patrick and Gwyneth Murphy, the trust's resident custodians, come over to check that I am settling in. Patrick shows me around the house. Things have barely changed here since King Love Pritchard, Bardsey's self-proclaimed monarch, evacuated the inhabitants to the mainland in 1925. With no electricity, cooking is by Calor gas stove and lighting by gas lamp and flashlight. Water is scarce, and must be filtered and boiled before drinking. Instead of a telephone - "You may be able to get a mobile signal from the top of the mountain," - there's a gas-powered klaxon for emergencies.
The loo is not exactly ensuite either. Patrick Murphy gestures to a bucket in an outhouse, with a box of grass cuttings beside it. "Put a handful on top after you've finished. When the bucket's full, tip it out into the compost heap here," he says, pointing to a wooden bin in the garden.
So it's not the last word in luxury accommodation. It's not even the first syllable. But it does have an earthy, back-to-very-basics appeal.
Within a day I am washing my hair in rainwater in the garden, swilling out my compost loo, and reading by the Rayburn in the gas lamp's pearly glow. Don't even think of coming here, though, if holiday happiness depends on the size of your showerhead - or, indeed, having a shower at all.
You can walk round the island in a couple of hours, but there is plenty to do. It's a wildlife lover's playground. The poet R.S. Thomas, who was vicar of Aberdaron, called it "a great draft of Nature". The fields are hazy with thrift and thyme. Fat Atlantic grey seals slob and snort on the rocks. And there are birds everywhere: the island's observatory charts the seasonal passages of choughs, oystercatchers, herons, peregrine falcons, wheatears, gannets, razorbills and shags.
Bardsey is especially famed for its 16,000 breeding shearwaters, nesting in burrows and flying furiously at night in rasping covens. The colony is home to the oldest bird ever ringed in Britain. This Methuselah of migrants, first recorded in 1957, is reckoned to have clocked up roughly five million miles on its winter passages to Brazil.
It's not just twitchers who come here. Visitors during my stay include a group of Christians on retreat, archaeologists excavating a Bronze Age burial, a creative writing group and a Canadian who describes himself as a fibre artist. Activities include boat trips with one of Bardsey's lobster fishermen, poetry readings, weaving workshops and services in the tiny chapel. In fact, there is more going on here than many towns on the mainland.
But the real appeal is the opportunity to slip down a gear, to slow down, and reverse a century or two. "Just doing the necessary things seems to fill our lives here. Everything takes so much longer," says David Barnden, who farms the island with his wife Libby.
The couple have had their share of dramas during their three years on Bardsey. On New Year's Eve 2001, Libby popped over to the shops on the mainland, but because of high winds she couldn't return until Valentine's Day, despite the best efforts of the Pwllheli lifeboat to reunite her with her husband.
It's a cautionary tale. Next morning the shipping forecast is prophesying high winds in the Irish Sea. If I remain another day I could be stranded indefinitely.
It's a classic mythical dilemma: leave now or you might never return to your world again.
I get a lift to the mainland with the lobster fishermen. Speeding back to the 21st century in a fan-tail of foam, I watch as Bardsey blows away into the sea, and feel a pang as if for the end of an idyll. Lucky old Merlin.
Getting there
Bardsey lies at the foot of the Llyn peninsula, north Wales. Ferries travel regularly from Pwllheli and Porth Meudwy, near Aberdaron, throughout the summer.
Staying there
Weekly or short-break accommodation is in self-catering houses, all without electricity, from around £120 per person for a three-night break. Further details from the Bardsey Trust (01758 760667; www.bardsey.org). Hikers can follow a 47-mile Edge of Wales walk along the ancient pilgrims' way to Bardsey, starting from St Beuno's Chapel at Clynnog Fawr.
Further information from www.edgeofwaleswalk.co.uk.