Some ultra-talented teenagers are lining up too, including Papamoa pair Mason Bryant and Andrew Trembath, Omanu's New Zealand under-16 ironman champion Sam Pasley and Mount Maunganui quartet Hamish Miller, Kane Sefton, Daniel Barron and Isaac Marshall.
"Not only is it a 25km stretch of incredibly beautiful coastline but it's a event with great competitors," Beattie, the 2012 and 2013 New Zealand ironman champion, said.
"Just things like jumping off that rock at the end of Moturiki Island - it's picturesque and there's no place in the world like it and to be able to race here is something special."
The women's field has had a late injection of Olympic class, with kayaking star Teneale Hatton signing up to race to get valuable cross-training for her flat-water pursuit.
She will link with a strong Piha contingent, with club coach and fellow 2012 Olympian Steve Ferguson having raced the inaugural Mount Monster last year.
Hatton's teammate, Kirsty Wannan, shapes as one of the women's favourites, alongside the Mount's Katie Wilson, who was second last year.
The forecast is looking ideal, with a 1m swell and light northerlies tipped.
Mount Monster
When: Tomorrow, 10am-12pm
Where: The race starts and finishes on Mount Maunganui's Main Beach
What: Mount Monster is a 5km beach run, a spectacular swim leg including a jump off Moturiki Island's blowhole, a 12km ski leg down to Omanu Beach and a 6km board paddle.