WHAT IS IT? The ultimate “room” with a view. A “portaledge” is a device used by mountaineers to get a night’s sleep when climbing in the Himalayas, Greenland and the like. It’s a lightweight canvas and aluminium platform suspended from bolts driven into the rock face. Hop aboard, sit back and enjoy the view.

WHERE IS IT? Located on a 500-metre-high rock face above the eastern shore of Lake Annecy, in southeast France. Reaching it involves a pleasant 30-minute hike through thick forest from the Col des Contrebandiers (“smugglers’ pass”) to the top of a cliff rising up from the lake shore; here you don climb­ing harness and helmet to rappel some 15 metres down to a wide, shrubby ledge. Off to the side is the portaledge, hanging serenely above a drop of several hundred metres. The views are sensational.

WHAT DO YOU SEE? Directly below is the village of Veyrier-sur-Lac, beyond which the blue-green waters of Lake Annecy glitter in the evening sunlight. On the lake’s far shore sits Annecy, one of the loveliest towns in the French Alps, and beyond that, range after range of mountains fade into the distance.

WHO IS IT AIMED AT? Those who don’t suffer from vertigo, obviously. If you do you’ll probably struggle to even get to your porta­ledge, and you certainly won’t enjoy the fondue and wine (in limited amounts, given the location) that your guide prepares on the ledge as the sun sinks below the horizon.

HOW COMFORTABLE IS IT? When you eventu­ally clamber aboard and slip into your sleeping bag you’ll probably be surprised at how warm and comfy you are, although you can’t realistically expect to sleep as soundly as a veteran mountain climber. For a start, you have to keep your climbing harness on – this secures you to the cliff in case you fidget your way off the “ledge” in your sleep. And, with the breeze blowing across your face and the incredible views, especially as the sun comes up, you’ll probably spend more time staring than sleeping.

WHAT TIME IS CHECK-OUT? That depends on when you wake up. And leaving is simple – after a continental breakfast while watching the early morning sun light up the lake, you climb back up the cliff, assisted by your guide, who has spent the night nearby. Once you’re back on top of the cliff, the day ahead offers the possibility of anything from a wander around Annecy’s medieval old town, with its attractive cobbled streets, winding canals and pastel-coloured houses, to a swim in Lake Annecy or a cycle ride along the 40km path that circumnavigates the lake.

WHAT’S THE BOTTOM LINE? Inax Aventure offers a night on the portaledge with guide, all mountaineering equipment (including sleeping bag) and dinner and breakfast for €290 (HK$2,500) per person (there is room for two).