If a guidebook tells you that something is “impossible to describe”, it usually means the writer can’t be bothered to describe it – with one exception. After pondering the views of the Grand Canyon for the first time, the most spectacular natural wonder on Earth, most visitors are stunned into silence. Committed travellers hike down to the canyon floor on foot or by mule, spending a night at Phantom Ranch, or hover above in a helicopter to get a better feeling for its dimensions. But it is still hard to grasp. The problem isn’t lack of words. It’s just that the canyon is so vast and so deep, that the vista stretches so far across your line of vision, up, down and across, giving the impression of hundreds of miles of space, that it’s a bit like looking at one of those puzzles in reverse – the more you stare, the more it becomes harder to work out what it is or where you are. Distance becomes meaningless, depth blurs, and your sense of time and space withers away.

The facts are similarly mind-boggling: the Grand Canyon is around 277 miles long and one mile deep. The South Rim, where most of the tourists go, averages 7000 feet, while the North Rim is over 8000 feet high – its alpine landscape only adding to the sense of the surreal. On the canyon floor flows the Colorado River, its waters carving out the gorge over five to six million years and exposing rocks that are up to two billion years old through vividly coloured strata. It’s this incredible chromatic element that stays with you almost as much as the canyon’s size, with the various layers of reds, ochres and yellows seemingly painted over the strangely shaped tower formations and broken cliffs. Think of it this way: the Grand Canyon is like a mountain range upside down. The country around the top is basically flat and all the rugged, craggy elements are below you. The abruptness of the drop is bizarre and, for some, unnerving. But the Grand Canyon is like that: it picks you up and takes you out of your comfort zone, dropping you back just that little bit changed.

The South Rim is open 24 hours a day, 365 days a year, the North Rim from mid-May to mid-October. See www.nps.gov/grca for more information.