Public transport is poor, and in high season the narrow roads are choked with caravans and motor homes.And then there's the weather You can rely on it to be totally unpredictable The summers are often wet and seldom hot The winters are either wild and cold or dark and drizzly. A few years ago, during a heatwave in May, an elderly local strode down Fort William's high street in full tweed suit and deerstalker hat Someone asked him why he was so attired. "Because we're going to pay for this," he replied, scanning the sky for the storm clouds that must surely be on their way, "and we're going to pay dearly."But the rain of the Highlands is a non-malevolent force. It seems to caress and nourish the skin, rather than scarify it. The air has a pine-cone purity and in summer the light is so sharp that you feel a layer of gauze has been removed from your eyes, enabling you to see things properly for the first time.By any standards, the Great Glen is a remarkable piece of geology. A 60-mile geological fault that (with the help of the Caledonian Canal) splits Scotland into two, from Inverness on the fringe of the North Sea, to Fort William, at the head of a loch that flows into the Atlantic.Loch Ness is the dominant physical feature ­ a gash so deep that it has defeated the attempts of scientists to chart it. When they tried to bounce a sonar beam off the bed to measure its depth, there were points, it is said, where the signal never returned.

The books have settled for an average of around 750ft: almost enough to engulf the tower at Canary Wharf, and more than enough to ensure that this relic of the Ice Age never freezes. Where better for a monster to lurk, for the most part unseen and undisturbed?Ah yes, the monster. Nessie is the reason most people visit the Glen, and she practically never fails to disappoint them. According to her official fan club, there were only four logged sightings in 1999, an all-time low. But still the tourists pour in, and even the sceptics find it hard not to scan the surface of the loch, just in case.The best vantage point is at the craggy ruin of Urquhart Castle, which sits on a promontory near Drumnadrochit and is surrounded on three sides by the peat-dark water. A new, £3m visitor centre and car park is nearing completion, the subject of much scorn for bringing concrete and commerce to a wilderness of rock and bracken. But something had to be done about the streams of traffic that were turning the A82 into a slower version of the M25 at rush hour.One American visitor at Easter, who had paid for the conducted tour of the castle (an important historical monument in its own right) demanded his money back at the end of his visit because the monster had failed to appear on cue.

In time, I believe, the Urquhart Castle development will come to be valued as the perfect way of corralling such Monster-hunters into a confined space ­ leaving the Great Glen proper to the rest of us.Loch Ness's dramatic beauty is most apparent when you step away from it and view it from afar. Weaving up the mountain above Drumnadrochit, a precipitous single-track road takes you to the hamlet of Bunloit, 800ft above sea level. A bend in the road just above the treeline suddenly reveals the giant, sugarloaf mound of Mealfuarvonie, a 2,300-ft peak which casual walkers can scale with ease in half an afternoon. At the top ­ as if summoned by central casting ­ sky, mountains, trees and water are laid out before you in perfect proportion to each other in an infinite variety of colour and tone. In a place like this, it's impossible to take a bad photograph. And from May to August, the light lasts for so long that you can carry on exploring long into the evening.An alternative route along the mile-wide loch is the B-road from Inverness via the less populated southern shore to Fort Augustus, the mid-point of the glen, and an ideal watering stop. This way, you dawdle through lonely farms and villages, stopping at waterfalls or viewpoints.Leaving Loch Ness behind, two lesser lochs ­ Oich and Lochy ­ lead you through the southern half of the glen, brimming with relics of history and pre-history.