The Red Bull X-Alps is often a race at altitude, whether athletes are flying or hiking on high trails and mountaintops. So how far can they see from these vertiginous viewpoints? As a very rough guide, to a man standing at sea level, the horizon will be around 5km away. At 30m, however, this increases to nearly 20km. To see 100km, you need to be standing at around 800m. This means that Christian Maurer (SUI1), who is at 1000m, should have a very clear view of the sea, which is just 55km away – as long as there's not a bigger mountain in the way, of course. Picture: zooom / Harald Tauderer.