"You meet all crazy people who do this type of stuff."
But he admits at more than 40km long and sitting at "between 13C and 16C at best" the Loch Lomond swim is set to be a big step up from anything he's done before.
"Less than 50 people have done it because it is so cold. It's much colder than the channel."
It doesn't help that they don't swim in wetsuits.
Mr Dawson has always been a strong believer in doing the events for charity - from his early Ironmans supporting various charities like Cystic Fibrosis to last year's channel swim which supported English spinal injury charity Aspire.
Over the past decade with the various events he thinks he's probably raised about $30,000 to $40,000 for charities while taking on the personal challenges.
He reckons the swim will be "about 50,000 strokes" and at 10c a stroke he's set a $5000 fundraising target.
Mr Dawson chose Rotorua's Hospice after seeing the amazing work they did looking after his mother for several days after she suffered a brain aneurism.
A date hasn't yet been set for Mr Dawson's swim, but with a small window when it's possible he was expecting it would be in August or September, around his 50th birthday.
"The record is 9 hours, 39 minutes. It's 40km so it could take me 10 hours but I think 11-ish would be my target."
So far the longest swim he's completed has been about four hours.
"We are all crazy, we really are."