Paralympian Ellie Simmonds has urged swimmers to take the plunge when the John West Great East Swim returns to Suffolk this summer.
The Great Swim Series, which manages the event, has partnered with the charity WaterAid - which has launched its 'Swim Marathon' challenge ahead of the summer.
Money raised for the charity will help provide clean water and sanitary facilities to communities all over the world.
The John West Great East Swim, held at Alton Water outside Ipswich, regularly attracts thousands of swimmers of all ages and abilities every summer.
However, the 2020 edition was one of many events that was forced to be cancelled due to the coronavirus pandemic.
It is set to return on Sunday, June 19 and will follow "strict Covid-secure procedures", according to the organisers.
Indoor swimming pools reopened on April 12 as part of the government's roadmap out of lockdown.
Ms Simmonds, a gold medallist at the 2008, 2012 and 2016 Paralympic Games, urged people to sign up for the swim in support of WaterAid, of which she is an ambassador.
She said: "I am excited to be able to support WaterAid with their new Swim Marathon and their partnership with the Great Swim Series.
"Believe it or not, I actually used to be terrified of swimming in open water, but I conquered my fear when I took part in a television documentary a few years ago and fulfilled my lifelong ambition to swim with dolphins.
"My life is often very structured that the feeling of freedom swimming in the ocean with these beautiful creatures remains one of the most amazing experiences of my life.
"Swimming is such an important part of my life and I think signing up for a swimming event is a fantastic opportunity to challenge yourself while exploring different beautiful venues, and there is the added bonus of knowing you are helping bring clean water to people around the world."
Marcus Missen, director of communications and fundraising at WaterAid, added: "We are delighted to have Ellie’s support for swimming challenges.
"Ellie is one of Britain’s most successful swimmers and water plays such an integral part in her own life and she has also seen the difference clean water can make in communities around the world. "
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