Organisers said amateurs competed alongside Commonwealth and Olympic medallists in Scotland's biggest open water event, held for the first time at Loch Lomond and the Trossachs National Park.
Participants took on half mile, one mile or two mile swims in calm, dry conditions.
The women's one mile race was won by Edinburgh-based Keri-anne Payne with a time of 18 minutes and 19 seconds.
European Championship Gold medallist Hannah Miley and Commonwealth Games champion Caitlin McClatchey came in fifth and tenth respectively.
Miley, 24, is the reigning European 400m individual medley champion while McClatchey, 27, took golds in the 200 and 400 metre freestyle at the 2006 Commonwealth Games.
Both pool swimmers, they were racing in the open water competitively for the first time and used the event as an opportunity to begin their training ahead of Glasgow 2014.
Winner Ms Payne said: "The water was lovely, it's such a nice course and a beautiful location. I was really pleased to win today, it was great."
Alex Studzinski from Germany won the men's one mile race with a time of 16 minutes and 46 seconds.
Commonwealth Games gold medallist Robbie Renwick came in tenth in his second ever open-water event. Renwick, 25, won gold in the 200m freestyle at the 2010 Commonwealth Games.
The event is part of the Great Swim series which has seen thousands of people swim in lakes and lochs around the UK.
Director Alex Jackson said: "It's been an absolutely incredible day at Loch Lomond. The enthusiasm and excitement of swimmers, supporters and spectators provided an amazing atmosphere from start to finish."