I left my lunch at Mawenzi Tarn

Not a catchy song title, just my first (but not last) encounter with Acute Mountain Sickness. I left dinner there, too, if a spoonful of soup, some water and a couple of anti-nausea ginger pills could be described as 'dinner'.

No, I didn't quite make it to the summit of Africa's highest mountain, but I did have a fantastic experience with a great bunch of people. Although it's a bit disappointing not to have reached the crater rim, I don't have a sense of failure – I gave it my best shot, walked all night from midnight to sunrise during the summit attempt and turned back only when I ran out of air and time. I climbed to about 17000 feet in the lowest temperatures I have ever encountered and saw some amazing views of Mawenzi and Kibo as well as looking down on the vast plains of Kenya and Tanzania when they weren't hidden beneath a blanket of cloud far below us. Each day of the climb was an adventure -- I enjoyed (almost) every minute of the trek. We narrowly missed meeting a herd of elephants on our trail and watched the gradually encroaching horror of a bush fire that followed us up the mountain for days, destroying vast areas of vegetation on the northern slopes of the mountain. We later learned our first two camps had been burnt out and the trail closed behind another group of trekkers who were just one day behind us. People who had booked our route after that were being sent up the Marangu or 'Coca Cola' route, which we later used for our descent. It's a pleasant enough trail to walk down, but can't compare with the spectacular drama of the Rongai route we took to the base of Kilimanjaro's second peak, Mawenzi.

Being incapacitated at Mawenzi was a big disappointment – having the opportunity to explore the base of the second, almost unclimbable peak was one of the reasons I chose the Rongai route. We arrived there in time for a late lunch, with the afternoon supposedly devoted to an acclimatisation hike up the lower slopes. Mawenzi Tarn is such a spectacular setting, with Kilimanjaro's only glacial tarn lying in a hollow below the towering jagged spires of the splintered volcanic cone. Its dramatic fissures are so utterly different from the more famous symmetrical dome of Kibo, Kilimanjaro's main summit. Kamili, our chief guide, told us he'd climbed Mawenzi three times during his life, but would never do so again as he considered it too dangerous even with ropes and modern climbing gear. Kibo just needs a good set of lungs and some reasonably fit leg muscles. Sadly, I was in no fit state to enjoy the scenery or a walk that afternoon, so I languished in my tent, convinced I was dying, while most other members of my group went off on the acclimatisation hike. The porters told me I would feel better the next day, but I didn't believe them, certain that if by some miracle I survived the night they'd have to drag me over the ridge between the two peaks to take me down to a lower altitude at Horombo camp – there are no real facilities to get casualties back down the Rongai route which is too steep and rugged for the single wheeled stretchers they use on the other side of the mountain. Of course, the porters were right – I not only survived the night, but felt fit enough to continue the trek to Kibo Hut the following day after eating (and keeping) a scoopful of disgustingly sweet porridge and some tea. I still couldn't quite face the bacon and eggs also on offer.

Surprisingly, my legs didn't let me down at all; no aching muscles, and the neoprene knee braces did their job so well I didn't have a twinge, even on the steepest descents. Even the shoulder gave no cause for concern when the guides became a bit too enthusiastic in their efforts to assist me up some rocks. Despite sleeping badly most nights due to sliding off my Thermarest mattress and then having to wriggle my way back up the incline like a caterpillar in my sleeping bag, I never felt tired except for the morning after summit night. It's ironic that my lungs let me down in the end – just couldn't extract enough oxygen from the thin air to keep me going.

I'll be posting a full trip report soon, once I am able to remain awake after 10pm. Spending two days and a night travelling home without sleep has left me unable to catch up even after four days. I recovered from climbing Kilimanjaro within twenty-four hours of descending, but sitting on planes, trains and mini-buses has left me completely exhausted. Or maybe it was just the horrible four hours spent at Nairobi airport – surely one of the most unpleasant places on earth.