A photo of around 300 climbers attempting to reach the summit of Mount Everest shows the kind of 'bottleneck' that could have contributed to four deaths last weekend.
Experts believe this kind of climbing 'traffic jam' also occurred at the Hillary Step, and could have been partially responsible for the deaths, according to the Daily Mail.
Ha Wenyi, 55, from China, Canadian Shriya Shah-Klorfine, 32, German Eberhard Schaaf, 61, and 44-year-old Song Won-bin from South Korea all had to use up precious oxygen supplies after waiting for three hours at the 40ft rock wall at 28,740ft for climbers to clear out.
The photo was taken by Ralf Dujmovits for Outside Online, and shows how congested Mount Everest has become.
Reports suggest that many amateur climbers keen to reach the summit pay sherpas to help them on their way - but are so keen to complete the feat, that they ignore their advice not to carry on when things go wrong.
This was allegedly the case with Shriya Shah-Klorfine, who was urged to to turn back by other climbers and by her sherpas.
She continued to the summit with a small amount of oxygen, which ran out on her way down, and her sherpas carried her until she died.
Teen becomes youngest person to climb highest peaks of all continents
British climber finds body of his friend at Everest summit