The BBC is retracing the footsteps of the 1953 British Everest expedition as they made their way up to base camp in preparation for the first successful assault on the mountain's summit. BBC correspondent Jane Hughes is keeping a diary of her journey.
Day Eight: Acclimatising in Dingboche.
When we set out on our journey to base camp, we expected to pass teams who had successfully climbed Mount Everest's summit and were on their way back to Kathmandu in celebratory mood.
This part of the world can be a busy place
But eight days into our trip, no summiteers have passed us. Though we're now well into the usual climbing season for the mountain, not a single team has yet made it to the top. Just looking at the mountain tells you why that is.
When it's not entirely obscured by cloud, it has a continual stream of white cloud pouring from its summit - a sign that the fearsome winds up there, which can exceed 200 kilometres per hour, are unrelenting.
Even where we are, two days walk from base camp, there is a wind rattling the windows of our guest house. Breezes down here translate into impassable gales 8,848 metres above sea level.
A record number of teams, around 35 in all, are hoping to reach the top of Mount Everest in this anniversary year. So that means several hundred frustrated people are encamped at base camp or higher up the mountain at the moment, waiting for a window of opportunity, a break in the weather when they might make it up to the top.
When the chance does come, there is likely to be a flood of people heading up at the same time, and that spells trouble. There are a number of bottle necks on the main routes, places where people use fixed ropes to ascend or descend, and can only do so one at a time.
One of the worst is the Hilary Step. A 14-metre rock ascent just below the summit which was one of the toughest challenges to present itself to Sir Edmund Hilary and Tenzing Norgay as they made their way to the top.
On busy days, climbers can wait two to two and a half hours to get up or down the step at the perilous height of over 8,000 metres, with their precious oxygen supplies dwindling as they wait.
A delay of that length can mean the difference between life and death. It was such a bottleneck that contributed to the disaster of 1996, when eight people died in a single storm high on the slopes of Mount Everest.
Two of the casualties were organisers of commercial expeditions, which help climbers who sometimes don't have much mountaineering experience to reach the summit.
Some of the groups waiting to summit now are also commercial expeditions - people who've paid up to $65,000 each to be guided to the highest point of the world.
Some argue that their inexperience and the pressure on their leaders to help them reach their goal creates extra dangers.
The latest anyone has ever ascended Everest is 29 May, the date of the 50th anniversary, so there is not much time left for the teams waiting on the mountain.
Many are now praying, as they are down here in Dingboche, that the 50th anniversary isn't overshadowed by another disaster like the one seven years ago.