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First ascent of Everest without supplementary oxygen

First ascent of Everest without supplementary oxygen
Who
Reinhold Messner, Peter Habeler
What
First
Where
Nepal (Mt Everest,)
When
08 May 1978

Reinhold Messner (Italy) and Peter Habeler (Austria) made the first successful ascent of Mt Everest without supplemental oxygen on 8 May 1978. This feat is regarded by some purist mountaineers as the first 'true' ascent of Everest, since overcoming the effects of altitude (i.e. the low oxygen content of the air) is the greatest challenge facing high-altitude climbers.