Some people makes it look like a walk in the park. Twice in one week without supplemental oxygen: http://www.kilianjornet.cat/en/blog/kilian-jornet-summits-ev

Some people makes it look like a walk in the park. Twice in one week without supplemental oxygen: http://www.kilianjornet.cat/en/blog/kilian-jornet-summits-everest-twice-in-one-week-without-supplemental-oxygen/ http://www.kilianjornet.cat/en/blog/kilian-jornet-summits-ev... Anyway, it's a good economic resource for those countries.