This year's victims succumbed to the perennial risks of climbing Everest - three Sherpas died in a serac or ice fall, and the others fell ill and died.

But the high number has renewed scrutiny on overcrowding after a record number of climbing permits were issued in Nepal, and deepened concerns about the impacts of climate change on the mountain.

Traffic jams
Locals in Nepal - the most popular jump-off point for climbers - attributed the unprecedented 900 permits to pent-up travel demand from the pandemic.

Having so many people puts pressure on "traffic jams" on the climbing route, Garrett Madison of US-based Madison Mountaineering company told Reuters news agency.

Lines form when mountaineers need to catch a window of favourable weather to reach the summit. They need to avoid jet streams or narrow bands of strong wind in the upper atmosphere. Queues can also be held up by inexperienced and unprepared climbers.

Extremely thin air on peaks higher than 8,000m (26,000 ft) makes it difficult to breathe and climbers often use oxygen canisters to survive, but logjams put pressure on supplies.