Click for video
Under immense pressure, Mount Maunganui kicked a penalty in the final 10 minutes before holding on to win 26-23.
The match got under way in explosive fashion on Saturday.
Mount scored the opening try, through flanker Matt Axtens, before hitting a drop goal from close range.
Whaka kicked a penalty and Chanse Perham crossed the tryline to make the scores 10-8.
First five-eighth Te Rangi Fraser missed the conversion but was clearly the danger man for Whaka, busting the line on several occasions.
Whaka halfback Akira Mako was sent to the sin bin for an intentional knock-on, and Mount took the advantage.
They kicked two penalties while he was off the field and held a 16-8 lead at halftime.
After the break, Mount scored a contender for try of the season.
Former Rotorua Boys' High School star Mason Walker took on two defenders down the right edge before offloading to Andy Devoy.
Devoy gave a no-look pass to Cayden Matehaere, who drew a player and linked back up with Walker. He pinned his ears back to score and the Mount fans went nuts.
But the momentum seemed to shift after that moment.
Whaka playmaker Fraser crossed the line and converted before his flatmate, Whaimotu Craft-Chemis, also scored a five-pointer for Whaka.
Arguably the quickest man on the pitch, fullback Craft-Chemis spotted a hole in the defence and took off like a jet plane.
In truth, he had done very little before that moment, but showed his quality with a 30m solo try. Fraser missed the conversion and the match remained 23-all.
Entering the final 10 minutes the tension was immense. No player wanted to make a mistake.
Mount held on to the ball well and forced their way down the park. They won a penalty and Matehaere slotted it, kicking a perfect six from six on the day.
Whaka tried their hardest to hold on to the ball in the dying minutes but Mount pinned them in their 22m and won the match.
Whaka coach Ngarimu Simpkins said he was proud of what his team achieved this season.
"That is finals' rugby at its best. We are really proud of our boys," he said.
"We couldn't quite do it but that does not take away anything from what they have achieved this year."
Whakarewarewa 23 (Chanse Perham, Te Rangi Fraser, Whaimotu Craft-Chemis tries; Te Rangi Fraser con, 2 pen) lost to Mount Maunganui 26 (Matt Axtens, Mason Walker tries; Cayden Matehaere 2 con, 3 pen, drop goal).