A surreal day out in Ireland

In the Wicklow Mountains you feel you're on another planet.

The strangest landscape in these isles is now 99 minutes from north Wales. To explain - on a seasonably clear day, you can see the Wicklow Mountains from north Wales. Until this summer, Ireland was a seven-hour round trip from Holyhead, and therefore out of range for a comfortable day out. But the new High-speed Sea Service - a very big, very fast ferry to Dun Laoghaire - opens up the east of Ireland to the daytripper.

Many of those tempted to make the crossing will head straight for Dublin, to celebrate Bloomsday one week from tomorrow, for example. Yet rewarding though the Irish capital undoubtedly is, for a surreal day out you should ignore the city and head straight inland - and upwards.

From the water, the Wicklow Mountains look winsomely pretty, a verdant fringe that arcs around the south of Dublin Bay before striding off in the general direction of Wexford. But within a 10-minute drive of the port, you can be scaling the time-blunted spine of some ancient Alpine range. Close up, the mountains are fierce.

The highway you are using was originally an instrument of oppression. Two centuries ago, the British built a military road due south from Dublin, and it yomps still across the mountains, giving modern tourist invaders access to some weird scenery. Draped between the ghostly peaks and crags that puncture the sky is a ruffled grey apron of granite. The suspicion that you have strayed on to another planet is reinforced by the signs of alien activity - disfigurement in the form of vaguely parallel lines scored into the land. Even today, peat-diggers still endure the chill and bluster to extract the remains of the forest that covered the mountains in mulch several millennia ago.

The terrain gains in height and might as you head south through Sally Gap, an empty crossroads with a scattering of signposts gesturing into the void. Take the one that orders a march across the moonscape to Glendalough, negotiate a sharp left-hand bend and suddenly the ground opens up beneath you. This is where a glacier began to gouge through the granite in a piece of heroic scenery-creation. The placid stream that has been accompanying your lonely journey suddenly changes into a roaring torrent, hurling itself down a near-precipice. The Macnass Falls looks like a bloody Niagara, because the peat stains the water the colour of savage rust.

The daytripper follows the highway that clings to the hillside before descending to a deceptively gentle valley. Glendalough looks like a typical Irish village - pub bearing gaudy Guinness advertisement earning disparaging glances from plain church, surrounded by a straggle of shops and cottages. But this rift in the mountains was the place from which Christianity was transmitted throughout the Celtic lands and into northern Europe.

If you believe the literature, St Kevin was born 1,500 years ago, and spent much of his life living a hermit's existence in Glendalough - first in a tree, later in a cave. He set a trend for piety that attracted followers from all over the island. A monastic settlement took root; Kevin became abbot at the age of 72, and endured for almost half a century longer. The statistics may be debatable, but the influence of Glendalough in the spread of the gospels is as tangible as the weary stones of the ruins.

The accurately named Round Tower presides loftily (from a height of 110 feet) over the remains of chapels, graves and a gatehouse. If St Kevin had set out to create the perfect tourist attraction, he could not have done better: the ambiance is accentuated by a lazy network of woodland paths winding up to a broad lake whose dark waters reflect the darker mountains.

Heading from here to the coast, the terrain shifts down a few gears from the grand post-Ice Age wreckage to the rolling, intensely green hills that adhere strictly to touristic stereotypes. At the shabby port of Arklow, daytrippers have to turn north for the journey back to Dun Laoghaire. For the first time since leaving the harbour there, you are within splashing distance of the Irish Sea - and some of Europe's finest and least-crowded beaches.

You may find it hard to imagine that within 25 miles of Ireland's main ferry port you can stumble upon a wide-open crescent of sand, population nil. The coast road to Wicklow is hard to find, a concealed turning from the main N11 highway, which could be why you encounter no one save the barman in an unsurprisingly empty pub. All Brittas Bay needs to become the big new beach destination is a dozen degrees of global warming; until that happens, you are able to enjoy the sea's aimless assault on the sand. That blur on the horizon is probably Wales, which reminds you that you are here for a few hours, not a fortnight.

The town of Wicklow, which lends its name to the mountains and county, fails to live up to their grandeur - probably just as well, since you have an appointment with a ferry. If you manage to elude the convoy of farm machinery that seems to impede the traffic on every Irish road I drive along, you will have time for a reflective glass of stout at the handsome old hotel opposite the harbour. Sip slowly as you marvel at the latest piece of world-shrinkage, and vow to stay longer next time.

How to get there

Stena Line (0990 707070) operates a high-speed service departing Holyhead at 8.55am, arriving in Dun Laoghaire just after 10.30am. The return journey at 8.45pm allows over 10 hours in Ireland. In June, a day-trip for foot passengers costs pounds 17 (children pounds 9). The lowest fare for a car and five passengers is the 48-hour ticket - pounds 134.

How to get around

Simon Calder rented a Fiesta from Malone's at 23 Lombard Street East, Dublin (00 353 1 670 7888), costing IRpounds 45 per day.

Who to ask

Irish Tourist Board, 150 New Bond St, London W1 (0171-493 3201).