The Jane Tomlinson Swim for All Yorkshire Swimming Festival will take place at Pugneys Country Park on Sunday, July 10.
The mum-of-three from Rothwell was diagnosed with incurable breast cancer in 2000 and given six months to live, but she battled on for seven years to raise almost £2m for charity with a series of challenges including triathlons, marathons and a 6,781km bike ride across America.
Her daughters Suzanne and Rebecca, and husband Mike, launched the event this week.
Mr Tomlinson said: “I am so excited that we’re launching a completely different event. Swimming was extremely important in Jane’s life and she’d be thrilled with an open water swim. She’d be the first to sign up if she was still here.”
The event will comprise of an open 500m and 1,500m swim and a 500m junior swim for 12 to 17-year-olds.
More than 1,000 people are expected to take part.
Mr Tomlinson, who confessed to being the world’s worst swimmer, added: “It’s going to be a spectacular day, whether you’re swimming or watching and we’re hoping it will appeal to people who don’t usually take part in the runs for all too.”
The event is open to everyone and it is sponsored by the Express, Wakefield Council, Real Radio, the Yorkshire Evening Post, Blueseventy and Wakefield Triathalon Club, which came up with the idea.
Entry fee is £20 for 500m and £25 for the 1,500m. Entries will be taken at www.swimforall.co.uk