SWIM Thru Rottnest founders David and Lynn Cummins will reward the 25,000th entrant to the annual swim with $200. The event, on Saturday, December 3, has raised nearly $180,000 for the Fiona Stanley Bone Marrow Transplant Unit. There is a 500m and 1600m event that starts off from Rottnest Island. The Cummins started the event on behalf of the Cottesloe Crabs Winter Swimming Club. Visit www.swimthrurotto.com.