Little wind with overcast skies meant good conditions for the swim with little chop on the surface.
"The conditions were great," said Boles, "although the visibility wasn't as good as it could have been - it was a bit cloudy."
The Legend of the Lake was the fourth round of the Ocean Swim series.
"I couldn't have asked for any better [conditions]," said Scott, who has won three rounds of this summer series, although that wasn't a specific target at the beginning.
"I'm happy with that," he said. "I'm training at high-performance up in Auckland and using these as swimming for the longer 10k stuff - the Aussie and New Zealand nationals have just gone and that's finished now until the end of the year, but these [open water swims] are to keep doing a bit of swimming that's not in the pool."
With the series now moving on the Christchurch before returning to the North Island for the Bay of Islands Classic in Paihia and King of the Bays in Auckland, Boles is unsure if he will make it to any other swims in the series as his focus turns to the New Zealand age group championships in Wellington next month.
"It's good to be able to represent Rotorua and just get out there and have a good time," he said.
Jackson Dawson was third in the men's race.
The women's race was won, as it was last year at the inaugural event, by Dunedin's Stefannie Gillespie.
"I realised about halfway through that I was the defending champion from last year - I'd only just remembered," she said.
"I just thought, try to keep going, I got on to a pack of boys and just tried to hang on to them as long as I could."
Swimming with others works in a similar way to drafting in cycling.
"It makes a big difference and you have someone to push you along as well. If you're out there on your own, you kind of get into a bit of a rhythm, but if there's someone right beside you or right behind you, you know you've got to push a bit harder."
Sammy Winward and Claudia Ashby were second and third respectively in the women's race. Gillespie plans to take part in all of the remaining three swims in the series.