Neil Gilson is undertaking a huge mental and physical task to raise awareness of a neuropsychiatric condition that affected his son Jack

The physical effort as he battles currents, coldness and wind is massive, but the mental challenge of ploughing on alone for hours on end is even more testing.

Neil Gilson, a father-of-three from Devon, is about to set off on the next leg of his attempt to become the first person to swim the 10 largest lakes in Switzerland, a total of about 230 miles.

If 39-year-old Gilson succeeds, Guinness World Records is expected to recognise him as the first to complete the “Legend of the Lakes” challenge and in subsequent years, other ultra-swimmers will try to do it more quickly.

Gilson, a former international swimmer, is undertaking the challenge to draw attention to a neuropsychiatric condition that affected his son Jack when aged 18 months. “It is a huge mental and physical challenge, but I’m determined to complete it to raise awareness of the condition that changed my son’s life,” he said.