Swim in Loch Lomond and then enjoy a MTB spin and mixed terrain run round Balloch Country Park. There are 3 options to choose from ‘The Wee Beastie’, ‘The Bikeless Beastie’ and the main event ‘The Beastie’:

The Beastie comprises a 750m swim in the Loch, 17k off road cycle (three big laps) and 5k run (two laps), finishing in front of the castle, sounds a lot easier than reality and a challenge for even the most experienced of triathletes.
The Wee Beastie a 400m swim in the Loch, 9k off road cycle (two smaller laps) and a 3km run (one lap). A proper wee toughie and a great way to start of before taking on the full Beastie another time, still a great achievement and not to be taken lightly.
The Bikeless Beastie Aquathon a 750m swim and 5k run (two laps), this year it is the Scottish Aquathon Championship.

Full details and rules of entry at https://www.entrycentral.com/festival/3405