A tribe of Oompa-Loompas have taken the plunge, The Wizard of Oz dared to drop and even Spartacus took to the pool.
Daredevils wearing fancy dress of every kind have made a splash during 10 years of The World Water Bombing Championships in Sheffield.
And as the event marks its milestone anniversary, organisers at MacMillan Cancer Research are urging more people than ever to take part as they aim to break the £10,000 fundraising total for the first time.
George Perkins, from Sheffield, has taken part since 2006 and, with friend Mark Phelan, has raised £9,053.
The 30-year-old said: “The most fun part for me is the fancy dress.
“Every year the standard gets better and better. In the past I have dressed up as a bomber pilot and Spartacus.
“I think you have to be ever so slightly mad to do this event, but it’s great fun.
“I first signed up after finding out that my father had cancer and was being helped by the Macmillan nurses. Sadly he passed away a couple of weeks after the event but I’m hoping that we can top £10,000 for Macmillan this year, so they can continue the fantastic support they provide.”
Teams from Chesterfield to Sheffield and even as far away as Buckinghamshire have taken part.
And for this year’s event, on May 7, there has even been interest from Australia.
Each team pays a £20 registration fee and aims to raise a minimum of £406 - which could fund two Macmillan nurses for a day.
To register, call 0300 1000 200 or email email@example.com to get a registration form.
Participants must be over 18.