Last year's men's champion, Marko Albert (Estonia), is not returning this year but women's defending champion Meredith Kessler (USA) will be on the start line.
Kessler is going for a fourth straight victory at the Taupo event. Other top seeds in the women's race include Kiwis Gina Crawford and Melanie Burke.
Kessler said it was a great event and something everyone should try and tick off.
"Taupo and New Zealand is a haven. It is a place where the pace slows in a positive way and we can take a step back and breathe clearly for a while."
Ironman New Zealand starts with a 3.8km swim in Lake Taupo, followed by a 180km bike ride and a full marathon.
Racing begins for the professional men at 6.45am, followed by the pro women at 6.46am, then the age group entries at 7am.
Top seeds in pro race:
Men: Cameron Brown (NZL) 1, Terenzo Bozzone (NZL) 2, Joel Jameson (GBR) 3, Nick Baldwin (SYC) 4, Mike Schifferle (SUI) 5, Dylan McNeice (NZL) 6, Andrew Yoder (USA) 7, Simon Cochrane (NZL) 8, Todd Skipworth (AUS) 9, Johan Borg (AUS).
Women: Meredith Kessler (USA) 1, Gina Crawford (NZL) 2, Melanie Burke (NZL) 3, Mareen Hufe (GER) 4, Stephanie Jones (USA) 5, Conny Dauben (GER) 6, Erin Furness (NZL) 7, Jocelyn McCauley (USA) 8.