Forty-one athletes from Omanu club, 36 from Papamoa, 26 from Waihi Beach and 16 from Whangamata would also be competing for top honours.
That includes Omanu volunteer lifeguards Devon Halligan and Molly Shivnan.
Shivnan, 15, is competing in her first Eastern Region champs after rising through the ranks as a nipper at age 4 or 5 to the senior level this year.
Last year, the teenager won gold in the board race at the National Under 14 Oceans Surf Life Saving Championships and hoped to mirror that success this weekend.
"I just love the beach and getting out in the surf. I love competing in these types of events, which are very challenging, but also great fun as well.
"I'm really looking forward to meeting all the other competitors from the different clubs who I'm sure are as passionate as I am about this sport."
Shivnan dreams of emulating the successes of Halligan, who is the New Zealand Black Fins vice-captain and winner of the Ironwoman competition last year.
"I want to go as far as I can in surf living, both as a volunteer lifeguard and an athlete."
Halligan, 25, moved back from Australia to live in Mount Maunganui in December.
"I love being back home and being able to fly the flag for Omanu [club]. I am really looking forward to competing this weekend."
Halligan said the battle for medals was going to be fierce, especially given the conditions.
"With about 1m swells expected it's going to be an interesting and challenging carnival."
Omanu head coach Simon Wills said Shivnan was definitely one to watch.
"Molly is one of our younger competitors who has come through our ocean surf programme and she has been able to quickly step up to the senior level.
"We have high hopes for her and all our other athletes this weekend."
Australian-based Omanu club members Max Beattie, who is the NZ Black Fins team captain, and Murdoch Finch were also competing, he said.
Surf Life Saving New Zealand Eastern Region sport manager Mark Inglis said the event was shaping up to be one of the most competitive this season due to the sheer number of athletes and their skills.
"To have 850 athletes from around New Zealand, including a lot who compete overseas, competing in Tauranga is simply fantastic."
The Rep Challenge attracts some of New Zealand's best athletes and having them compete alongside athletes at the ERC's, means it will create a lot of close racing."
Eastern Region Championships:
Mount Maunganui Lifeguard Service: 75 athletes
Omanu Surf Life Saving Club: 41 athletes
Papamoa Surf Life Saving Club: 36 athletes
Waihi Beach Lifeguard Service: 26 athletes
Whangamata Surf Life Saving Club: 16 athletes