Demand for holiday homes suggests many Irish people regard them as a 'must have'. Orna Mulcahy dips her toe in the expanding, and sometimes very expensive, market.

Harbour Cottage on Long Island - that's Long Island off Schull, west Cork, not New York - is the sort of bolt-hole that people fantasise about. Postcard pretty, it's a two-bedroom whitewashed house, bang on the water's edge on a tiny island with just nine inhabitants in Roaringwater Bay.

A mile off the coast from Schull, the cottage is set on half an acre of gardens, with brilliant views from every window. The house is in apple-pie order inside, with a fitted kitchen by Clive Nunn and cosy attic style bedrooms. The asking price? €240,000 to include a Land Rover for bombing around the island and 16 ft boat for shopping trips to Schull.

At least that was the asking price when Harbour Cottage went on the market three weeks ago, before the bidding began in earnest. Sherry FitzGerald O'Neill is about to agree a sale at a substantially higher price, such has been the interest.

"We've had very busy viewings," says sales agent Caroline Maslin, who says that most of the parties were couples from Dublin looking for a second home. "There is big interest in this sort of property, because it's so pretty and unusual, and yet it's close to a fashionable village."

In Donegal, meanwhile, Letterkenny agent Paul Franklin has been walking prospective buyers over a rare seven-acre waterfront site with planning permission for a lavish 4,000 sq ft house at Doah Beg near Portsalon. The last viewer came up from Dublin by helicopter to admire the views.

"It took him less than an hour to get here, and of course, with the tremendous wealth coming out of the south, the site is relatively good value," says Franklin who expects to get more than €300,000 for the property when final bids are submitted on August 20th.

In Connemara, Tony FitzGerald of Sherry FitzGerald Kavanagh, waxes lyrical about about a five-bedroom modern house at Laontaois beach, overlooking Killary Harbour and Inishturk Island. A beautiful wild and windy spot near Tullycross, it's also wildly fashionable with well-heeled Dubliners, hence the asking price of €700,000.

Prices are steep too on the Mayo coast where Done Roman, a five-bedroomed bungalow in a stunning setting at Carrowcally Point near Westport is on the market at €530,000 through the ERA J. O'Donnell agency.

In Brittas Bay, Co Wicklow, there are ready buyers for mobile homes on 10-year leases at the exclusive Jack's Hole beach. Beachfront "vans" change hands for over €200,000 a go, with annual services charges of €8,000.

Further down the coast, demand is strong for chalets and cottages by the sea. "This is our busiest time in terms of demand and viewings," says Ciara Slattery of Warren Estates, a Gorey, Co Wexford agency that specialises in homes along the popular seaside stretch from Ballymoney to Castletown. "People are calling all the time looking for holiday homes along the coast. It's almost as if a holiday home is a must these days."

Slattery, who says that old-fashioned cottages are especially hard to find, has several holiday chalets on her books, including a small three-bedroomed chalet with the dreamy address of Parsley Lane, by the sea on Castletown. The asking price is €220,000. It might sound like a lot to pay for a small wooden house, but for Dublin buyers with small children and big equity in their main home, it's an affordable buy.

Thanks to the boom in house prices over the past eight years, many homeowners now have so much collateral their home - the difference between what they paid for it, five, 10, 20 years ago, and what it is now worth - that they can afford to splash house on a second home. Somewhere that will cost them €150,000 upwards, that they can enjoy getting away to, that they might well retire to, and that in the meantime could well appreciate in value.

While there are no exact figures for holiday home ownership, it's clear that many of the country's most scenic locations are full of them. Go to Roundstone, or Brittas Bay, or Schull in the middle of winter and the lights will all be turned off.

Prices throughout the country have been creeping up in line with the booming economy, with waterfront property the most sought after. "Anything with a foreshore, people are gobbling up," says James Lyons O'Keeffe, who has agencies in Schull and Skibbereen.

"Further back and in the country it is slower. People don't want to be off in the middle of nowhere. If we had 20 houses in the village for every one in the countryside, we could sell them more quickly."

Caroline Maslin agrees, "People want to be within walking distance of a village. Even two miles out is considered too far these days."

Right on the sea in Kilmore Quay, Co Wexford, is Aisling Cottage - a traditional thatched cottage that has been given a thoroughly modern makeover by Kevin and Catherine Dundon, proprietors of Dunbrody House Hotel. The three-bedroomed cottage is in the middle of the fishing village, and has a sunny decked garden at the back.

Inside there are lots of unexpected comforts such as underfloor heating, and a high spec kitchen. It's on the market through Kehoe & Associates at €375,000.