More than 1,000 people have signed up for a military-style endurance challenge and mud run at Newark Showground.
Organisers of the Airfield Anarchy event say they will comfortably surpass the 1,000 participants initially expected and may have to cap entries at 2,500 if people sign up at the current rate.
The run, which covers both 5km and 10km routes, will take place at Newark Showground on March 22.
The site is being transformed into a treacherous 20-obstacle course featuring mud pits, hay-bale towers, rope swings and freezing water.
Monkey bars over water, a climbing wall and a tyre wall are the latest additions.
The event is in aid of the RAF Benevolent fund that helps RAF personnel and their families.
It will be the first Airfield Anarchy event in the UK.
The showground was chosen because it is the former RAF Winthorpe base, which was used for Lancaster bomber training during the second world war.
Event director Mr Greg Goodall said: “It is all coming together really well. We have already reached the 1,000 people mark and we are still expecting a lot more people.
“The course is taking shape as well and should provide people with a real challenge.”
The event will also have its own radio station that will broadcast event information for 48 hours before, during and after the race from a 50 metre aerial on the back of a truck.
People can enter as individuals or as part of a team. The race will set off in five waves due to the numbers.
There will be on-site camping and entertainment including live music, a bar, hog roast, children’s activities, military displays and an after party.
For more information and to enter visit www.airfieldanarchy.com