My first ultra was the North Face 100km. From there, no turning back, just looking for longer, higher, hotter, colder and more extreme.
Desert running in South Africa, extreme heat and sand takes it's toll. Heat exhaustation, dehydration, hypernatremia and having to drink your own pee. You can't drink too much (more than 3 days) and it's best to wait for it to cool down so easier to drink!
The altitude stuff takes it toll because of less oxygen in the blood and can take a while to acclimatise. Leadville USA a special race, the himalayas in India and running above base camp at Everest. Grand Canyon truly awesome.
Sometimes the odd problem, hypothermia from being too cold or not managing food intake. Cleared of High altitude pulmonary oedema (HAPE) in hospital far north India.
Canada Solo bike ride
Really enjoyable experience! Rode from most easterly point of Canada (Cape Spear, St Johns) to Vancouver which was 7777km and took 46 days. A massive iceberg in St Johns, very impressive. Went through all weather conditions including a tornado behind me a major storm above me and snow in front of me. Slept on the side of the road in a tent. Raise money for 100 mile club to promote health & fitness for school kids.
It took me a while to realise why no-one was cycling the same direction as me east to west, it's easier the other way because the wind is behind you! Problems with a coyote one night wanting to share my food.
The Arctic circle in Northern Canada, preparing for the ice roads on the Yukon river. Making a brew. I remember finishing this race and sitting down thinking how hard this was to manage the cold and problems with equipment. I said to myself "I want more of this, I want to do the poles."
Too often you have to get your back into it, but the view is sensational. This was in the top of Norway.
Usually remote, so peaceful and technically difficult are the ice/snow adventures. The gear required is neccessary for survival because no matter how fit, strong or experienced you are; the weather is a critical factor which effects you and your equipment and your capacity to continue.