“SO LET’S get this straight,” frowns the 11-year-old, poring over our shiny new map. “We’re starting in the north, but it’s actually the south, then going south - into the north?”

It is not as confusing as it sounds. Our two-centre driving holiday in Ireland begins in Donegal, which is in the north of the country but is actually part of the Republic of Ireland. The road will then take us south, including along part of the spectacular Wild Atlantic Way, into Northern Ireland, where we’ll end up at the city of Belfast.

It is a lot to pack in, so as soon as we disembark from P&O’s handy Cairnryan to Larne ferry, we pick up our hired car from Dan Dooley, and get on the road. Initially, we head inland through the green countryside of Antrim, and the boys have fun following the map and pointing out interesting-sounding place-names (like Moneyneany, Killaloo, Ballymagorry and Pluck).

We’re only dipping into the Wild Atlantic Way, which stretches all the way from Donegal’s towering clifftops and sleepy fishing villages to the dreamy bays and tiny coves of Kinsale. But the bit we do experience (all the while making a mental note to come back another time to do some more), across the rugged Fanad peninsula and up through Carrickart, is jaw dropping in its wild, windswept beauty.

There is plenty for families to see and do around here, too, like beautiful Glenveagh National Park, with its deer, lakes, glens and castle; or the pretty village of Ardara, where you can discover the story of Donegal tweed; and the awe-inspiring Sliabh Liag cliffs, the highest (at 600m) marine cliffs in Europe.

A sudden burst of near-tropical weather helps us make the most of beautiful Downings, with its pale golden sands and clear blue-green water. It’s the perfect place to stretch our legs after the long drive from the ferry and Archie and his little brother, Harry, are soon lost in a world of sandcastles, shell-hunting and splashing in the sea.

The area is steeped in golfing history – our home for the next few days, Rosapenna Hotel, was once billed as the "world’s first golf resort" and its fascinating past, which stretches back to 1893, is revealed in old photographs, letters and newspaper articles around its walls.

Nowadays, when not welcoming famous golfing faces like Rory McIlroy, Rosapenna provides guests with a slice of modern-day luxury and the friendly staff warmly welcome all guests (including little ones) whether they are former Open winners or not ...

From the warm sands of Rosapenna, we wind our way back to Northern Ireland, and our first stop is its jewel in the crown, the Giant’s Causeway.

This geological wonder continues to boggle the mind, although our boys, who read up all about it before the visit, are refusing to suspend disbelief as the guides unravel a tale of warring giants and strange sea-crossings, huge babies and mysterious, magical stones.

“It was all about volcanic eruptions, there’s no magic,” dismisses the seven-year-old, although his eyes widen just a little bit as our lovely guide, Rebecca, points out the ‘chimneys’ on the cliff, said to smoke once a year on Christmas Day when the giant is at home; and he still leaves a coin in between the rocks, where magic is supposed to lurk, for good luck.

After clambering over the basalt stone columns (hexagons, almost without exception, although we spend a long time looking for the nine-sided one which the guides assured us was out there, somewhere amid the 40,000) we head back up the hill to the visitor centre, a beautiful new building which blends into the landscape, with walls of glass, basalt columns and a state of the art interior.

Here you can learn all about the science behind the Causeway, with interactive exhibits, a cafe and gift shop and it’s well worth a visit.

(It’s worth pointing out that your ticket price includes parking and entry to the centre but not the bus which runs down to the Causeway itself – that’s a local service which charges for non-National Trust members. You can, of course, walk down to the Causeway, bypassing the centre and its admission charges, for free – but you won’t be able to use the centre’s car park. You would have to get a local bus or find somewhere else to park nearby and options are very limited.)

As well as the Causeway, there is much to do and see in Antrim, from dramatic Dunluce Castle, whose history can be traced back to early Christians and Vikings, to bonnie Glenariff Forest park, with its waterfalls, and rocky gorges. We fit in go-karts and assault courses (child-friendly ones) at Watertop Farm in Ballycastle. Still a working hill farm with 600 sheep, it now opens to visitors during holiday periods, with a variety of activities on offer including boating, walks and trails, pony-trekking and sheep racing.

After a stop in Ballycastle for lunch and some more beach time, we head back, enjoying more coastal scenery. It is so clear and sunny, the views across to Rathlin Island and beyond are breathtaking.

“Is that Scotland?” asks Harry, impressed by news the Mull of Kintyre is visible on a good day. “Can we see our house from here?”

It feels a long way from the lapping waves at Rosapenna to the busy waters of the River Lagan in Belfast. This is the vibrant waterfront of a city reborn, a bustling buzz of a place, full of life and colour at the best of times and overflowing with excitement during our visit thanks to the arrival of the Tall Ships.

On the last day of our holiday, our destination is Titanic Belfast, a brilliant attraction packed full of information about the world’s most famous ship.

Constructed at the cost of £97 million and opened in 2012, the museum (shaped like a ship’s bows) comprises nine galleries over four floors.

It is cleverly laid out, telling the story right from the beginning, from the reasons why the Titanic was built in booming Belfast, through the electric atmosphere at the launch, to the terrible events of April 14, 1912 and beyond.

It is fascinating, eerie at points (especially the 3D tour, with the help of giant screens) and very moving. Reading the distress calls as the Titanic crew tried in vain to reach other ships, listening to the survivors’ stories and the tales of those they lost, is sobering for us all.

It is extremely well done, with just the right balance of fun and respect.

On the boat home, after a few days away that felt like a fortnight, Harry sums it up. “It feels like we have had six holidays rolled up into one,” he sighs.

City, seaside, science and wonder, history and folklore – Ireland has much to offer, whether you head north, south or both at the same time.

How to get there:

P&O Irish Sea (http://www.poferries.com/) runs regular sailings between Troon and Belfast, and Cairnryan and Larne. Prices start at £267 for two adults and two children.

Car hire for a comfortable four/five door car for four days starts at £375 including insurance from Dan Dooley (0800 282 189, info@dooleycarrentals.com). The company does not charge extra for crossing the border between the Republic and Northern Ireland

Where to stay:

A family room at the Causeway Hotel in Bushmills (028 2073 1210 www.thecausewayhotel.com) costs from £89 per night, bed and breakfast.

A family room at the Rosapenna Hotel and Golf Resort in Donegal (0353 74 91 55000 www.rosapenna.ie) costs from £140 per night.

For more information:

To discover more about the Wild Atlantic Way visit www.wildatlanticway.com

Entry to Watertop Farm (www.watertopfarm.co.uk 028 2076 2576) costs £3 for adults and £2.50 for children but extra charges apply to activities too.

Admission to the Giant’s Causeway (including access to the visitor centre, a guided walking tour or audio guide, orientation leaflet and parking) costs £9 for adults and £4.50 for children (National Trust members go free). A shuttle bus from the Visitor Centre to the Giant's Causeway costs extra 028 2073 1855 www.nationaltrust.org.uk/giantscauseway.

Tickets for Titanic Belfast cost £15.50 for adults and £7.25 for children www.titanicbelfast.com

For more details on holidaying in Ireland, visit www.ireland.com and www.discovernortherireland.com