Mich Kemeter, 23, managed to navigate his way safely across the thin tight rope in just under two minutes with a 650ft drop beneath him.
Mr Kemeter was forced to battle gusts strong enough to knock him off balance as he quickly hotfooted it 65ft to the other side in front of stunned onlookers.
The impromptu attempt without any safety gear was captured by photographer Pedro Pimentel, from Cardiff.
"Mich just disappeared from the path we were walking back on after a climb," he said.
"Then suddenly I noticed he was already walking on the line set up for some highline attempts later that day.
"The whole thing was over before I even had the time to properly realise what had just happened in front of my eyes.
"The risks were obvious – but Mich is one of the best at what he does. he has no fear."
