The definitive proof about Snake Canyon's ability to defy the scorching sun came in the form of involuntary shivering. Three hours earlier, at 10am, the temperature had already been verging on uncomfortably warm as we headed into this slot canyon located in Oman's Hajjar mountains, midway between Al Ain and Muscat.
But as the canyon narrowed to a few metres wide and the smooth, ochre-coloured walls towered 100m or more above, the temperature quickly dropped. Soon we were clambering over rocks and jumping into pools of crystal-clear water to make progress, and the further into the three-km--long gorge we went, the longer it had been since the water had been warmed by the sun.
Some of us began shivering and rushed onwards to where the gorge began to open up ahead, seeking sun-warmed rocks to hug. Those who had taken the advice to wear wetsuits went from having faintly mutinous facial expressions early in the gorge to looking ever so slightly smug.
As if the prospect of hugging sun-warmed rocks was not bizarre enough, the final evidence about how different life deep in an Omani gorge is compared with the UAE's coast came when a quirk of geography sent a zephyr of warm air from the outside world to where we were standing. Unusually it was greeted with relief rather than despair.
Just beyond the gorge, the temperatures were uncomfortably warm and we had to seek the shade of a date-palm plantation for our post-canyoning barbecue. But we managed to find another option for cool temperatures by driving over the Hajjar Mountains to near the top of Jebel Shams, Oman's highest peak. The actual summit is an off-limits military zone but we found somewhere to camp a little way below, where the altitude of nearly 3,000m did almost as good a job at keeping the temperature at a moderate level as had Snake Canyon's precipitous walls.
Our campsite was not a place for sleepwalkers: just off to one side was the Middle East's biggest canyon, a kilometre-deep gorge where ancient rainfall had created a V-shaped notch in the uplifted sedimentary rock.
Even when the sun blazed down on us the next day, it was still a comfortable temperature as we headed along a rough hiking trail known as the Balcony Route, located just below the crest of the canyon and heading towards an abandoned village called Sap Bani Khamis.
The village's location is the perfect illustration of just how much life has changed in the sultanate in the past 50 years. Back in the tribal days, defence was one of the primary considerations, and so 15 families had once chosen this site on a steep, rubble-strewn terrace between two bands of cliffs to eke out a meagre but defendable existence. Once central government was established, the families abandoned Sap Bani Khamis in favour of much easier terrain on the plateau above.
We were here partly to visit the old village, where architectural remnants like intricately carved doors and an old millstone sat amid the crumbling old homes sheltering under an overhang. If all this was improbable enough, it was nothing compared to the other reason we were here: the Sticks Route, which the villagers used to use as a short cut through the cliffs to the plateau above. The name came from their habit of jamming sticks into cracks in the cliff to make the climbing a little easier and safer.
A few weeks earlier, many of our group had done the Stairway to Heaven, a similar villagers' short cut between a wadi in Ras al Khaimah up to the plateau villages just across the border in Oman. The route has a ferocious reputation for being steep and exposed, but the trail is fairly obvious, linking the line of least resistance using natural ledges and occasional drystone staircases.
But compared with the Sticks Route, Stairway to Heaven looked like Sheikh Zayed Road. From afar, I was puzzled when I couldn't see an obvious route through the cliffs above Sap Bani Khamis. Once I was up close, I found out why: there isn't one. Fortunately for us, a series of steel cables and metal foot- and hand-holds had been installed along the Sticks Route. This is what is known as a via ferrata, Italian for "iron way"; the term originates from the First World War, when the front line between the Italian and Austro-Hungarian forces was in the alpine crags of the Dolomites.
For modern-day recreational climbers equipped with basic mountaineering equipment, via ferrata such as this one effectively provided all the exposure and fun of climbing with none of the risk. Or so I hoped. With us were Rob and Justin, guides from Muscat Diving and Adventure Centre who run trips up the Sticks Route. Not people who are easily cowed by mountains, they were clearly in awe of the Omani villagers who used to use this route to get to the plateau.
"People would have died here," Justin said. "This is a serious rock climb. If you fall, that's it."
Their job was to make sure we did not follow suit, which meant instructing us on using two short pieces of rope tied to our harnesses so that we were always connected to the steel cable at any given time, limiting any potential fall to a maximum of only a few metres.
With the cable and occasional metal spikes drilled into the rock, the route was just on the tricky side of easy. But the whole way up, I couldn't help thinking about the mindboggling courage and skill of all those who had done this without any kind of rope for safety.
After about 60m of steep climbing, we emerged onto a rubble-covered terrace and followed it to the next line of cliffs, where yet another steel cable safeguarded our passage to the plateau above. From there, it was an easy walk to where we had parked the cars. At a viewpoint just beyond, the locals now hawked interesting pieces of rock to tourists and I struggled to imagine their grandparents' generation scaling the cliff without the aid of hefty wire cables.
If not for a chance encounter the previous day in Snake Canyon, I might never have been able to envisage one of those hardy types who used the Sticks Route. A few minutes after we had headed into the canyon, our group had encountered a smiling and clearly very fit young man who lived in one of the villages just upstream. He introduced himself as Adnan and it was obvious he had travelled the gorge dozens of times - his ideal way to spend his Friday morning was to accompany groups like our own.
Where we were brought to a halt and had to downclimb stacks of boulders and contemplate using the safety rope we had with us, he ambled across it as if he was walking through Marina Mall. Where we would jump into the pools of water, he'd find a high-level traverse on smooth, steeply sloping footholds and leap across from one side of the gorge to the other as if he was immune to the laws of physics.
Any mountain cred we might have aspired to have through choosing Snake Canyon as a day out evaporated in the face of such a display of skill. It was like watching David Beckham taking part in a football match alongside a group of uncoordinated eight-year-olds.
The whole way Adnan was smiling as if he was in the best adventure playground imaginable. Which, I suppose, he was.
After a couple of hours, he headed back to attend Friday midday prayers in his home village and we completed the gorge, still marvelling at the display of skill that gave a hint of why Omani villagers had discovered and used short cuts like these.
If you go
The trek Muscat Diving and Adventure Centre (www.holiday-in-oman.com/; 00 968 2448 5663) runs via ferrata trips on the Sticks Route and through Snake Canyon for 59 Omani rials (Dh590) per person.