Swimmers from across the Royal Borough will gather at the Magnet Leisure Centre on Saturday for an all day charity swim.
Organised by the Lions Club of Maidenhead, the 28th Maidenhead Swimarathon will see teams of sponsored swimmers attempt to complete as many lengths as possible in each 55-minute time slot.
It will run between 7am and 9pm.
Entry is now closed for the event, with more than 100 teams registered. Organisers hope to raise £32,000 for good causes.
In 2013's Swimarathon more than 700 competitors swam a combined distance of about 200 miles.
The 111 teams raised more than £30,000 for more than forty charities.
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