Sailor Alex Thomson walks along mast of Hugo Boss yacht off coast of Cadiz

That was the honest revelation made by Hampshire’s sailing superstar Alex Thomson after successfully managing a highly dangerous stunt.

As can be seen in these pictures, the round-the-world yachtsman – who was third in last year’s epic Vendee Globe race in a British record 80 days – first balanced on the mast of his 60ft boat at the height of a ten-storey building.

He then climbed higher and higher above water level while his boat, HUGO BOSS, is moving through the water off the Spanish coast near Cadiz.

When the yacht listed at 60 degrees, Alex clambered to the tip of the mast and dived into the sea.

The 39-year-old had been planning his mast walk for months.

“We have been planning this trick for a very long time,” he said.

“There were lots of things that could have gone terribly wrong.

“The wind could have pulled me off the mast and catapulted me onto the deck; I could have hit the water at the wrong angle or surfaced too quickly.

“These were all factors we needed to consider far in advance.”

Alex, who is afraid of heights, added: “Luckily, we succeeded in pulling it off.

“The stunt was far more dangerous than I would ever have imagined. “I can honestly say that it was the most stupid thing I’ve ever done in my whole life!”

Alex’s stunt coordinator, Andy Bennett, said: “There are countless things that can go wrong. The mast is incredibly long, and the strong wind pummels the yacht from every direction.

“Every time the mast moves, Alex could lose his grip and plunge to the deck.”

A medical team was on hand at all times while Thomson walked on the mast, while divers on board a rubber dinghy sailed alongside the yacht.

This was not the first stunt Titchfield-based Alex has pulled off. A video went viral in 2012 after showing him scaling the orange keel of his yacht from a speedboat.