A team of 50 people will be swapping grease paint and theatrics for cycle helmets and wetsuits as they enter the Blenheim Triathlon.
Pegasus Theatre, in East Oxford, has enlisted 50 supporters to run, swim and cycle around Blenheim Palace for the weekend of June 9-10.
It is part of the theatre’s 50th anniversary celebrations.
And with each triathlete being set a fundraising target of £500 for the theatre, it is hoped their efforts could net £25,000.
Chairman of the trustees Becky Hall, 43, from East Oxford, will be among them.
She said: “Pegasus is such a brilliant place.
“When I heard they were doing this great thing for their 50th birthday, I thought it would be a really good way to keep fit at the same time as supporting Pegasus.”
She said she was impressed by the number of people – most of them competing in such an event for the first time – who had signed up.
Mrs Hall said: “I think it’s absolutely brilliant, it shows how important Pegasus is to so many people that they are prepared to get so wet, cycle so far and then run at the end of it.”
Karen David, 50, from Oxford city centre, has also signed up to take part.
She said: “I think it’s a great way for Pegasus to raise funds and for people to get on and do a challenge like this.
“It’s a good, exciting way of getting everyone involved.”
Pegasus patron Philip Selway will be touring with his band Radiohead during the race, but visited the theatre on Friday to lend his support to the triathletes.