Winger Jone Macilai backed himself on the left flank after swatting away Michael Collins before stepping on the inside and heading to the tryline.
But it was Otago that went to the sheds, leading 12-10 after Josh Timu scored following a lineout drive.
The son of dual New Zealand international John Timu showed good strength by dragging Taniwha defenders Kara Pryor, Nock, and Jonny Cooper to the tryline.
Evergreen Nasi Manu took the field for Otago in the 55th minute to add more bite to their attack but Northland wouldn't give an inch.
The Taniwha will meet the winner of tomorrow's clash between Hawke's Bay and Taranaki in the Championship final next weekend.
- Northern Advocate
Northland 32 (Jone Macilai, Jordan Olsen, Sam Nock, Matt Matich tries; Johnny Cooper con, 2 pens; Wiseguy Faiane 2 cons)
Otago 19 (Jona Nareki, Josh Timu, Sio Tomkinson tries; Josh Ioane 2 cons)
Halftime: 10-12
Here's how the match unfolded: