Triathlons are hard enough if you have 20/20 vision and are taking part on flat ground and calm water.
Red Szell, 49, an adventurer from Hampstead who suffers from a degenerative eye condition called retinitis pigmentosa, has only 5 per cent vision - and his version of a triathlon involves a hair-raising tandem bike-ride, a 60m scramble down a cliff, swimming 30m across the gap, and then somehow climbing to the top of a sea stack the height of Nelson's Column.
All on the very edge of Scotland's wild northern coast.
And - remember - Red is registered blind.
"I think, since I started climbing, I have always aimed to complete the set. There are these three great sea stacks," he told the Ham&High.
Red has just returned from conquering the imposing Am Buachaille - the third, and most challenging, of three most famous Scottish sea stacks.
This time the attempt was particularly poignant too, as Red and his team were attempting a climb while and old friend - Martin Moran - was missing, presumed dead, in the Himalayas.
Red had already climbed the other two - the Old Man of Hoy and the Old Man of Stoer.
Off the coast of Sutherland looking out towards Orkney, Am Buachaille is a crag climbing landmark set where the North Sea meets the Atlantic Ocean. And even getting there is difficult enough.
After Red climbed Hoy and Stoer, this was the obvious end to a trilogy, but a first attempt in 2015 ended almost before it began - he was forced to turn back by extreme winds and tides.
The Hampstead dad said: "Honestly, it was almost a relief. After hiking blind across 10km of broken, boggy ground I was mentally and physically exhausted.
"I needed a better plan. I hadn't appreciated until I had my first recce out to Am Buachaille just how extreme the approach to it is."
The setback was far from terminal though, and thinking outside of the box is, he said, one of Red's skills.
He continued: "One of the beneficial side-effects of having the disadvantage of being blind is you get used to being a problem-solver and finding work-arounds. So I started plotting and planning ways of getting around this - and came across this international award..."
Last year. Red won $25,000 from the San Francisco LightHouse for the Blind charity's Holman Prize, which is named in honour of another blind adventurer: James Holman and with the money, Red was able to put a team together and plan for a serious second attempt at Am Buachaille.
He already owned the tandem bike he would need to get across the headland more efficiently, and with sighted climbing partner Matthew Wootliff, experienced moutaineer Nick Carter and filmmaker Keith Partridge, everything was set for another go.
But fickle Highlands weather almost put paid to the attempt. "We went up on the Tuesday but ended up having to wait until the Saturday, our last day." he said.
After driving out to the car park which marked the beginning of the journey, Red jumped on the tandem bike, and fell of a few times, - "we had a few cuts and bruises" - on the way to the edge of the headland.
Then there was the small matter of getting to sea level.
Red said: "The 200ft climb down a pretty steep rock was terrifying. Frankly at this stage I didn't feel much of a disadvantage not being able to see. Then came crossing the rocks - it was like an extreme obstacle course.
"Getting into the sea was the relaxing bit. I am quite used to cold water because I swim in the Highgate ponds regularly. I also knew the worst was behind me."
Compared to the cycling and scrambling, scaling the face of Am Buachaille was back in Red's wheelhouse, but once you get to the top there's only one way to go.
"You don't have the time to enjoy it, then," he said. "You know you've only got a limited time to get back down and do it all again in reverse because of the weather!"
Red got back to Hampstead in one piece though, and looking back at the project he said: "It pushed me to the limit."
He also thanked the Holman Prize for making his attempt happen.
He said: "It's open for any blind person with an idea for an adventure and it's helped me achieve things I would never have thought possible.
"I have never managed a project before!
"It's about challenging perceptions of what's possible for people without sight, and the idea is believing there should be no barriers to adventure."
In memory of Martin Moran
When Red climbed the Old Man of Hoy and the Old Man of Stoer, Martin Moran was with him and the team.
Martin, a vastly experienced climbing expedition leader adventure was tinged with sadness - the guide who helped Red to summit both the Old Man of Hoy and the Old
Sadly, Martin was leading the expedition to the Nanda Deva East ridge in the Indian Himalayas when he vanished, along with seven others, in an avalanche.
The team were hoping to climb a previously unconquered peak in the range.
The bodies of his companions were found, but this week rescue teams called off the search for Martin.
Red said he, Nick, Matthew and Keith paid tribute to Martin at the peak of their climb.
He added: "He helped me reach heights I would have never thought possible.
"He was never going to be with us this time, because he was going to the Himalayas, but the four of us who all knew him pretty well - perhaps Nick best of all - shared a toast for Martin."
Martin Moran, lost in the Himalayas, was born in North Tyneside before moving to run a mountaineering firm in the Scottish Highlands.
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