Now studying at the University of Waikato in Hamilton, Miller has some experience in the triathlon ranks having placed nationally at New Zealand secondary schools level and winning the national aquathon title in 2015.
After making the New Zealand youth surf life saving team in 2016, he chose to put his focus on the ocean realm, mostly because it didn't involve two wheels.
"I used to hate biking - I'd hop on and my legs would be dead by the 10km mark. This winter, I've been really focusing on getting some solid biking and running under my belt and now that I've got a little bit fitter at it, I can actually manage a 50-60km ride now. I'm enjoying it and the new type of training and the new challenge is really going well."
Miller's main competition this weekend is expected to come from his Mount Maunganui clubmate Declan Dempster, who was runner-up and under-19 winner last year.
Dempster is just back from helping the Junior Black Fins to an historic world title in Adelaide and, together with the likes of Coolangatta Gold short-course champion Joe Collins (Fitzroy), should push hard for the title.
Defending women's champion Rachel Clarke won't be back to defend her title as the New Zealand ocean ski star will be competing in Sydney at the 20 Beaches Ocean Classic instead.
The leading female contender is likely to be Lyall Bay teenager Ella Kingi, who finished third in 2016 and second last year.
The teams division continues the strong multisport theme - defending team champions The Shark Tank comprise top New Zealand kayaker Kurtis Imrie, leading open water swimmer Matt Scott and Commonwealth Games triathlon medalist Tayler Reid, alongside Black Fin Andrew Trembath.
ITU world cup triathlete Anneke Jenkins will also line up in a team, as will teenage cross country star Sam Tanner.
Previous Mount Monster winners
2017: Hamish Miller (NZ), Rachel Clarke (NZ)
2016: Luke Cuff (Australia), Danielle McKenzie (NZ)
2015: Ben Cochrane (NZ), Kirsty Wannan (NZ)
2014: Max Beattie (NZ), Kirsty Wannan (NZ)
2013: Cory Taylor (NZ), Danielle McKenzie (NZ)
Race records
Luke Cuff (2h 16m 33s, 2016), Danielle McKenzie (2h 25m 46s, 2016)
- Supplied content