LOCH Lomond plays host to one of the toughest endurance races in the world today, as 80 elite athletes prepare to run and swim from one side of the loch to the other and back again.

The Swim Run UK is, according to organiser Alan Anderson, an event for those “bored by ironmans and triathlons”.

The athletes will start off in Arden, swim over to the Balmaha at the other side of the loch via four islands before then turning around and swimming over to Luss via another six islands.

The ten runs and ten swims will add up to about 35km (21.75 miles) for each of the competitors. “We’re expecting the fastest people to do it in five and a half hours and the slowest people to do in nine hours” Anderson says.

“Ten islands, ten swims, ten runs. It’s basically swimming in a wetsuit with your trainers on and then running in a wetsuit with your wet trainers on. And you’ve to run up a mountain.” he says. “It’s for bored ironman triathletes. It’s the fastest growing sport in Europe at the moment. It’s gone from one race in Sweden 10 years ago to 60 all over Europe this summer.”

The first swim run in Sweden was started by four friends who drunkenly bet each other to see if they could make closing orders in a pub at the other end of the archipelago by the next day. From that, Ötillo was born. Now every year more than 200 people take part.

Earlier this week the Loch Lomond and The Trossachs National Park revealed that open water swimming in its 22 lochs is at an all-time high.

This year over 2,600 people took part in the Great Scottish Swim and wild swimming in the loch this summer has boomed.

Gordon Watson, chief executive officer at Loch Lomond and The Trossachs National Park Authority, said: “We are looking forward to welcoming the competitors this weekend for the Loch Lomond Inch by Inch competition..

“It doesn’t matter if it rains” says Anderson, “all we need to worry about is the wind. If the wind comes from the east it means big, big waves. Luckily, according to the forecast it looks like it’s coming from the west.”