It’s when my “indestructible” stainless steel water bottle launches out of my daypack like a rocket and smashes on the riverbed below that I realise just how perilous my situation has become. I’m halfway up a cliff in the Sacred Valley of Peru, about an hour and a half north-west of Cusco, and the only thing stopping me from joining my smashed bottle below is a harness and a clip. I know it’s enough to keep me safely tethered to the wall, but the sight of my water bottle gives me a sudden swirl of vertigo… (continue reading on The Guardian).