Kiwi mountaineer Guy Cotter first climbed Mt Everest in 1992. A professional guide for his company, Adventure Consultants, he's summited the world's highest mountain four times since. He's also, twice, been forced to turn back. He tells the Weekend Herald what it's like to conquer this pinnacle of human achievement - what it feels like, what it takes, and what it gives in return.
There are hundreds of sunrises before you plant a cramponed boot onto the highest place on Earth.
But you've climbed through the night to reach Mt Everest just before the beginning of a new day - the culmination of a year's preparation for this moment, including the six to eight weeks making the attempt - and this sunrise will be the most spectacular yet.
Under your feet in this tiny space about the size of a small garage is the whole world, and it's a magical sight.
You can see the curvature of the Earth. You can see lightning storms — not above, but below.
You can see the shadow of Everest stretched out across the lower peaks of the Himalayas, mountains that are giants in their own right.
The air is thin up here at 8850m but, if you've timed your summit inside a good weather window, that air isn't too cold.
In the five times I've reached the summit of the world's highest mountain, the temperature's been around -5C, warm enough to remove your gloves.
You can take your oxygen mask off for a bit too, which takes you out of your own little world and allows you to share the emotion with those around you.
Here, on a tiny patch of ground flanked by a 2500m drop on one side and a 3000m drop on the other, you can finally enjoy the achievement you've been building up to for a year, one you haven't really allowed yourself to believe is going to happen until you're almost at the top.
Even at the Hillary Step you're still 20 to 40 minutes from the summit, and then you have to go over a series of humps which mean you can't really see very far.
But then you come around the corner and the summit is only 200m away. Suddenly it's like it comes on so quickly.
You feel joy and relief, but it's more than that because you have a feeling that you wouldn't have if you were just teleported to the summit.
It could never mean so much, because standing on the summit is just a moment in time.
You realise "I've done it", but it's a feeling that's about the entire journey to Everest.
The final part of the journey, which takes up to nine weeks door to door, starts with an eight or nine-day trek to Base Camp, 5300m above sea level and challenging enough on its own for some.
We make it comfortable for people, but Base Camp is on a moraine, which is where rocks have piled up on a glacier.
It's like living on a gravel heap. A gravel heap that sometimes moves under you, too.
This is a place where bumps in the night, or the day, aren't unusual. You can hear distant avalanches and rockfalls. After a while you can determine even in your sleep whether something is hazardous or not.
You become attuned to the environment.
After a week acclimatising, it's time to move on to Camp 1, 600m higher and reached by crossing the famously tricky Khumbu Icefall.
It takes about eight hours to make your way across the ice fall, where at the start of the climbing season each April/May local guides, nicknamed "icefall doctors", have gone ahead to secure a route through this moving river of ice.
The effects of high latitude are constant — headaches, reduced energy, insomnia, lack of appetite.
There's a lot of talk that Everest is just these walkways with ladders, but there's a lot more to it.
You're hypoxic most of the time. Your muscles shrink; I usually lose between 10kg and 12kg each Everest expedition.
After a couple of nights it's on to Camp 2, at 6400m, for a few nights, where the jet stream blasts over the peaks and, sometimes, into Camp 2, blowing tents away.
That's not fun, but the views are pretty special here — you can see Lhotse, which is the fourth highest mountain in the world at 8516m and Nuptse, which is just under
8000m. And our Camp 2 is parked under the massive Southwest Face of Everest.
That's three giants of the Himalayas, so it's pretty spectacular.
When you leave Camp 2 you begin making your way up the 1500m high Lhotse ice face towards Camp 3, before turning back a third of the way up.
This is as far as we go on our first acclimatisation phase. Go any higher and our bodies won't cope.
It might sound strange going up and down, instead of pushing on, but if you don't you won't eat or sleep well, or your body may just shut down.
You have to go back to the thicker air in Base Camp to recover.
After a week to recover we return and this time climb to Camp 3, which is in the middle of the Lhotse ice face and is just a ledge cut out of the ice for tents.
It's a very uncomfortable place, although there's an awesome view.
It's not time to push on to attempt the summit of Everest just yet, though. Again you retrace your steps, all the way back to Base Camp, where you wait for a weather window to return back up the mountain.
This back and forth journey takes place over about six weeks and is vital to getting your body accustomed to the high altitudes. You've got to develop more red blood cells, which are your oxygen-carrying cells.
The next rotation is the summit phase.
When the forecast looks promising, we go straight past Camp 1 to Camp 2. After checking the weather again we continue to Camp 3 and then, the following day, make our way to Camp 4 at an area known as South Col, which is just under 8000m above sea level.
Summit day begins between about 9pm and 10.30pm, so you can climb the final 1000m to the summit by dawn the following day.
The timing is not just about your arrival, but also about giving you enough time to safely get back down again.
From South Col it's on to the Triangular Face, the Balcony, the southeast ridge to the southeast summit and then onto the summit ridge, which includes the Hillary Step, an almost vertical rock face.
I've seen the media reports this week about congestion near the summit, which I think was caused by a combination of factors, including a short weather window.
I've never experienced congestion like that, but I have found myself behind people on the way up to summit. If my clients are up to it, I'll clip around and pass them.
There's usually one slow person who doesn't pull over. They're the sort of people who, back in the outside world, would speed up while driving in a passing lane.
I first climbed Everest in 1992, becoming the 412th person and ninth Kiwi to reach the summit, and I'd describe the experience of staying alive while climbing Everest as being in a constant state of paranoia.
What's the weather like? Is it still good? How much oxygen do we have?
You're constantly re-evaluating.
It's like a meditation. You have to shift everything else out of the way so you can focus on your survival.
But I'm also aware that we're not changing the world — we're just going to a geographical high point.
Climbing Everest does change you, though.
Part of it is accepting death. When you do something like that you know death is a potential outcome.
If you are not cognisant of that you may not be cautious enough and end up as a statistic.
Most people spend most of their lives pretending death isn't real. But you come back from an environment where death is your partner, and it's like holding a big mirror up to yourself.
You are forced to acknowledge your strengths and weaknesses and work on your weaknesses.
When you take those final steps onto the summit and the skies don't part, there's no special message coming out of the clouds for you.
The magic is in the bonds you create with those with whom you shared the adventure. It is only when you return to the outside world the impact of the experience hits you.
You see a bit of green grass, a pretty flower. Or you have some nice food or sleep in a real bed.
You've climbed to the highest place in the world, and it makes you appreciate the small things in life.