Compléter Kilian Jornet - cloze C1Version en ligne Cloze test par Maria Milan 1 again sea ropes food almost ultra days oxygen guides of right climbing only supplies get probably ascend people 26 people When you picture mountain climbers scaling Mount Everest , what comes to mind are teams of climbers with Sherpa leading them to the summit , equipped with oxygen masks , and tents . And in most cases you'd be , as 97 per cent of climbers use oxygen to to Everest's summit at 8 , 850 metres above level . The thin air at high altitudes makes most breathless at 3 , 500 metres , and the vast majority climbers use oxygen past 7 , 000 metres . A typical group will have 8 ? 15 in it , with an equal number of guides , and they'll spend weeks to to the top after reaching Base Camp . But - distance and mountain runner Kilian Jornet Burgada ascended the mountain in May 2017 alone , without an mask or fixed for climbing . Oh , and he did it in hours . With poisoning . And then , five later , he did it , this time in 17 hours .