Caledonian waterway: Walk the breadth of Scotland with a little help from a Flemish barge-turned-passenger boat

Iskimmed down the kit list: waterproof jacket and trousers? Check. Thick socks? Check. Walking boots and woolly hat? Check. Slippers...? Slippers? I've been on a few walking holidays over the years, but I've never been asked to pack my slippers before. I slipped them into my backpack.

I was about to tackle a coast-to-coast trek in Scotland: a 77-mile hike through the Great Glen, the geological gash that slices the country in half from Fort William on the west coast to Inverness in the east. I pictured rain-lashed tramps up sheer boulder-strewn slopes, sodden boots stuck in boggy ground and ankle-grabbing heather. It wasn't, I thought, a put-your-slippers-on kind of holiday.

How wrong can you be? As soon as I set foot on Fingal of Caledonia, a jaunty Flemish barge-turned-passenger boat, I was enveloped in a cosy, mug-of-steaming-tea, welcome. This is a holiday for people who love the great outdoors, but not in a hard-core way. If you want to put your feet up (and your slippers on) when the blisters bloom, that's fine.

Fingal of Caledonia steams back and forth along the Caledonian Canal from April to October. Designed by Thomas Telford at the beginning of the 19th century, this watery highway connects the Atlantic Ocean with the North Sea. Its 60-mile length comprises a series of freshwater inland lochs and 22 man-made miles of canal, with 29 locks and 10 swing bridges along the way.

The "Walk the Great Glen" trip is one of a number of holidays offered on the barge: the company also runs wildlife cruises, music weeks and multi-activity cruises with walking, cycling, sailing and canoeing. The vessel is stocked to the gunwales with equipment. All I needed, though, was my feet. The Fingal Way is a specially adapted version of an existing long-distance route, the Great Glen Way; it adds the odd detour and extra hill to climb. You use the boat as your base and hike manageable 10-to-15-mile chunks each day while the boat cruises along the canal to meet you.

The first day was a gentle eight-mile amble. The official Great Glen Way starts at the fort in Fort William, which sounds good until you realise it's outside McDonald's. So instead for the Fingal's Way variant we headed down to Corpach Sea Lock for an apparently traditional toe-dipping ceremony in the Atlantic – well, Loch Linnhe, at least.

While Fingal chugged up the canal to Gairlochy, where we were to spend the first night, we wandered along the towpath to meet it via Neptune's Staircase. This is a ladder of eight locks that raises the canal 64 feet in a quarter of a mile. Bracken, the boat's dog, a sheepdog cross, lolloped beside us. The snow-capped Ben Nevis range reared up to one side.

Fingal was built in 1928 in Belgium and worked as a cargo vessel along the Rhine. Martin, the skipper and owner, discovered the old wreck in a boatyard in Fort William in 1993. Together with boatyard owner Don Hind, he rescued her and converted her into a passenger boat with six cabins and started running cruises in 1996. Last year, they upgraded the cabins, which now have bathrooms and under-floor heating. The rest of the boat is surprisingly roomy, with a comfortable saloon and an open-plan galley.

The crew is a big, happy family. They hug a lot. Rob, the first mate and guide, is cheerful even when it rains. His encyclopaedic knowledge of flora and fauna, animal droppings and the more gruesome bits of Scottish history lightened our struggles up calf-burning mountainsides. Then there was Ed, the fresh-faced new bosun, and Tree, the rosy-cheeked cook.

Martin doubled as skipper and the ship's entertainer: before he rescued a barge, he was an actor. After each belt-busting dinner, he would grab his guitar and we would sing sea shanties and old Beatles medleys into the night.

On our second day, a sunny Sunday, we set off from Gairlochy to hike 12 miles along Loch Lochy to Laggan Locks. The walk weaved through woods and along quiet country roads. In the afternoon, we threaded our way along forest tracks, the banks scattered with daffodils, primroses and violets.

Day three was tougher: 13 miles from Laggan Locks to the town of Fort Augustus. The first part through woodland on the banks of Loch Oich was next to an old railway. A detour to the Thistle Stop café for scones and cappuccinos stoked us up for the steep climb to the top of Meall a Cholumain. Every time we stopped to take a breath, the views got wider – and from the top we could see all the way to the Moray Firth in one direction and Loch Linnhe in the other. Scrambling down into a gully and up the other side, we spotted a herd of deer.

The rain was sleeting down on day four, so I put on my slippers. I wanted to experience life on the barge, as it descended through the locks from Fort Augustus to Loch Ness. I sat up in the wheelhouse with Martin as we sailed up the loch to pick up the walkers.

Boots back on, day five was another steep schlep from the youth hostel at Alltsigh to Drumnadrochit. We climbed through thick forest and then made our way along country lanes down to Drumnadrochit where we were picked up from the beach that lay near Urquhart Castle. A short cruise to Foyers where we were anchoring for the night and then, as the sun broke through, we strolled up to the falls to experience a local optical illusion: if you stare at the thundering water then flick your eyes to the side, the rock wall seems to move upwards.

The last long day (15 miles) covered the most diverse terrain. After a breakfast cruise, we wound our way up through Narnia-like forest tracks and then out on to bleak open moorland before trundling down through gentle woods thick with rhododendrons and scattered sunshine. For our final dinner, Tree cooked us haggis, neeps and tatties, and Martin gave the address to the haggis in knife-wielding style.

As Fingal chugged into Inverness the next day, we strolled along the towpath to the end of the line. Boots eased off, toes wiggling in relief, we dipped our feet in the salty waters of the Beauly Firth.

'Fingal of Caledonia' (01397 772167; caledonian-discovery.co.uk) has limited availability on the six-night 'Walk the Great Glen' trip starting on 3 and 17 October this year, price £595 per person. Next year the trip runs on 10 and 24 April, 19 June, 7 August, 4 and 25 September, for £675 per person, full board