Solo ride in the South of Switzerland today. Approx 1km from the nearest person. 1600m (1 mile) long pitch black tunnel at 1300m altitude. Lockable gate at both ends and no phone reception. Troutie Lumen Liberator light. Very wet and cold inside the tunnel. Was a lot of fun although I have to admit that the idea of someone locking the gates at both ends did pass through my mind, as well as the slightly less extreme but more likely scenario of my light failing!
On the far side of the tunnel there was a big landslide which was impassable so I ended up coming back through the tunnel. Rest of the ride was spectacular though!