ONE of Britain's biggest endurance contests starts with a splash tomorrow.

The tough Enduroman Chesil takes place over three days, during which competitors will undertake a 17-mile swim, a 150-mile cycle and a 52-mile run.

The 219-mile total is 78 more than athletes have to cover in the famous Ironman contests.

Although only in its second year, it's 50-strong list of entrants is nearly double the number who competed last year.

Last year's winning time was more than 30 hours - including a ten-hour-long double marathon - set by Steve Gershon, who returns this year to defend his trophy.

Competitors who do not quite feel up to the main distance can race over half the course - an eight mile swim, 75 mile bike ride and full marathon.

The 17-mile swim starts from West Bay at 8am on Friday - or at noon from Abbotsbury for the half-swim - and follows the length of Chesil Beach to Chiswell on Portland.

The island's Sailing academy then hosts the start of the double marathon at 8am on Saturday - noon for the single distance.

Competitors finish on Sunday with a circuit of Dorset - taking in some of the county's most arduous hills. Race organiser Eddie Ette said: "This is the first time that a marathon has been held here since the mid-eighties and we are all hoping that people will be at the Sailing Academy to cheer them home as they arrive between 3pm and 5pm." Safety cover for the swimmers includes an accompanying canoeist for each competitor, and several rigid inflatable boats that will patrol the course.

A spokesman for Portland Port, the main sponsors, said: "Eddie Ette's energy and enthusiasm in organising this challenging competition matches his personal record in endurance events.

"We wish the competitors the very best of luck in what will be a gruelling competition."

A spokesman for UK Athletics, which is not connected with the event, said: "This is clearly a very challenging event. Endurance events are becoming more and more popular."