SISTERS Claire Finter and Jayne Moyle endured rough seas, stingers and sunburn to complete their marathon charity swim from Great Keppel Island to Yeppoon on Sunday.
Their pain meant an $18,000 gain for the Alzheimer's Australia Dementia Research Foundation.
"We want to thank the community who really got behind us," Claire said yesterday.
"We were aiming to raise $10,000 but we've raised just over $18,000. The support has just blown us away."
The siblings were motivated to do the fundraiser because both of their maternal grandparents had suffered dementia.
The sisters started their swim at 5.30am in relatively calm conditions. But by 11am, they were being battered by rough seas and being dragged off course by a strong southerly sweep.
They arrived at Yeppoon just after 2pm, greeted by the cheers of a 200-strong crowd.
"It got very windy and very rough. The waves were quite big," Claire said.
"According to Google maps, the official distance was 20km but we probably ended up swimming closer to 24km because of the conditions."
They were also targeted by stingers. While Claire suffered only a couple of stings, Jayne was stung about 15 times.
The sisters were flanked by four support vessels and Claire's husband Daniel kayaked alongside them.
They stopped every 30 minutes for a medical check and for food and water.
Jayne opted for energy gels but Claire ate sandwiches smothered with her dad's home-made "mandaquat" jam (so named because the cumquats he grows in his garden are as big as mandarins).
Claire said they clocked up 30km to 35km, in the pool and open water, to prepare for the event.
The charity swim was the longest they had done.
Claire and Jayne are both gifted swimmers. Jayne recently represented Australia at the World Triathlon Championships in London in September.
"It's been a skill of ours since we were kids. We thought we would put that skill to good use and we smashed it," Claire said.
Both are recovering well from the marathon swim. Claire was nursing a sore right shoulder but said sunburn was probably the biggest issue for them both.
"The muscle soreness has not been too bad. The last few days has been about getting our bodies back to normal nutrition. That's the biggest challenge."