Not quite like our picture, the zorb-like vessel was powered, like a hamster wheel, by running and pushing at the walls inside, while a metal frame featured paddles to drive it forwards and footballs provided extra buoyancy.

With just a few protein bars on board, the adventurer was planning on catching fish during his voyage.

However, he contacted coast guards on Wednesday, saying he had concerns for his own health.

He activated his emergency radio beacon on Saturday and was transferred to a Coast Guard station where he was found to be uninjured but suffering from fatigue.

In the past Baluchi has raised money for charity by running the perimeter of the United States in about six months, and by spending seven years cycling through 55 countries and six continents.

According to his website, his mission is to “inspire us and unite us as a people”, and this specific challenge raised funds for children’s charities.

Tenacious or plain crazy? Let’s just hope he keeps his schemes on solid ground from here on out.