`They have to fill up the lakes somehow," says David Begley, manager of the Manor House Hotel in Killadeas, near Enniskillen. It's raining in the lakeland county of Fermanagh. Water everywhere. At the hotel, there's a beautiful swimming pool, all airy light and glass, but I haven't brought my togs. A hopeful inquiry at reception's lost property for a left-behind costume yields up only an umbrella.

Like all counties across the Border, Fermanagh's tourism has been affected over the years by political instability. The tourist brochures bravely try to make the lack of visitors a positive aspect about the county, by referring to Fermanagh as "the best kept secret of Ireland". If the Northern Ireland Tourist Board is successful, Fermanagh and other counties will be open secrets to all. The NITB is currently trying to remind citizens of this State that there are many interesting places to explore north of the Border.

Fermanagh's defining feature is its lakes. More than one-third of the county is under water and the tourism operators are turning this to their advantage. As well as the cruise boats that ply the Erne loughs, there is also the Shannon-Erne Waterway. This opened in 1994 and runs from Belturbet to Leitrim, a distance of 63 kilometres. You can rent the compact floating caravans that are canal boats and drift downwater for a week or more at a time.

Corraquill Cruising presently has three barges for hire. The initial leg of the southbound journey is from Corraquill Lock No 1 to the village of Ballyconnell.

New to me is the method of opening and closing locks - all done automatically by inserting credit card-like pieces of plastic into control boxes at the various locks. It's a gentle way to travel, watching sprays of blackberries and rosehips star the riverbanks and the odd disgruntled heron slowly unfolding its wings. If you're not staying aboard, you can rent one of the lovely Corraquill country cottages and use them as a base to explore.

The main town is Enniskillen, forever associated now in the world's consciousness with the bombing that took place a decade ago on Rememberance Day by the Cenotaph. The statue now has 11 doves flying from its plinth; a simple and poignant tribute to the lives that were lost.

Enniskillen itself is on "the narrows" - the thin bit of land between Upper and Lower Lough Erne. There's a turretted castle to explore, as well as a craft complex called the Buttermarket, and the Ardhowen Theatre, which has a gorgeous waterfront setting. Blakes of the Hollow might sound like something out of The Hobbit, but it's a wonderful old pub on the main street.

There are several large rambling houses open to the public in Fermanagh. Among them is Castle Coole, near Enniskillen, a huge neoclassical pile. It's unusual in that there has never been an auction of any of the house's contents. Over coffee and scones in the kitchen, Patricia Donald, who works there, tells stories about the Belmore family, who still live on the estate. "And there's one good thing about the effect of the Troubles," she says, pragmatically. "You wouldn't get too far down the road with a truckload of furniture without coming to a security checkpoint."

This means that Castle Coole still contains its original period furniture and china. Among the pieces are plates in the dining room which are decorated with pictures of ferocious-looking tigers, rhinos and elephants. Perhaps the loveliest feature in this huge and rather daunting house is the Regency fireplace, all intricately pleated and tasselled white marble.

At Trory, there are boats which will take you on the 10-minute trip across to Devenish Island. The island is the site of a 6th century monastery, and still has the remains of a tiny church and abbey. From the mainland, at Trory, what you can see most clearly is the 81 foot high round tower, still in perfect condition. The tower is open to members of the public who possess a head for heights.

Those monks must have been nifty fellows, especially when you consider that they also had the garb of their voluminous habits to contend with. There are four long and very steep ladders to the top.

At the top of each ladder is a tiny wooden platform, where monks sheltered themselves and their possessions from the enemy. Climbing ladders is definitely more taxing on the legs than that other medieval method of ascension, spiral stairs. There wasn't time to go fishing, but as we walked down to the island's little museum, we could see a boatload of anglers landing a catch. Their voices carried across the water, so we could tell what it was they had caught - that tough and crafty fish, the pike.

Necarne Castle, near Irvinestown, is a happy example of how a building and its setting can be recycled for other purposes. Now empty, the Castle provides a foil for an award-winning state-of-the-art Equestrian Centre that's been built around its outbuildings and courtyards.

The last occupant of the castle moved out in the 1940s, when it was used as a hospital during the war. Later, the castle became an enormous co-op when hens were installed by way of avoiding the taxes dues on residential buildings. It's inevitable that there should be resonances in many place-names across the Border. On the second night, we ate dinner at the lakeside Killyhevlin Hotel outside Enniskillen. Almost totally destroyed by a bomb in the summer of 1996, it reopened for business this summer. According to David Morrison, the general manager, they're flying.

Perhaps most memorable of all was a visit to Boa Island. Boa Island is a lick of land that lies in the north of Lower Lough Erne. It's connected by road to the mainland and thus accessible by car. On the island is Caldragh Cemetery, which you reach by walking down a grassy lane between petrified whitethorn bushes. The cemetery has a wild, abandoned feel to it, all weeds and sinking headstones.

Caldragh is famous for the Janus figure that hunches within it, staring out at all who pass with a strange, unsettling gaze. Nobody is quite sure how old this two-headed Janus figure is, or the smaller and more weathered figure beside it, but it's thought they date from the first century. There is a small crevice between the two heads of the Janus figure that was filled with rainwater and coins on the day I was there. Both the cemetry and the surrounding farmland are on Douglas Rowe's land. "People started leaving coins in the hollow about two years ago," he says. From time-to-time, the money vanishes, lifted by visitors. Rowe shrieks with laughter as he tells of receiving a receipt from Christian Aid for the sum of £41. Some zealous punter had donated to Christian Aid the money found in the hollow of what's generally believed to be a pagan idol.