Unfortunately for the Bay, they lost forwards Pingi Tala'apitaga and Shahn Eru to injury in quick succession, with the latter returning to the field for a few minutes before being substituted.
It was two big blows for the Steamers who were also missing captain Culum Retallick.
Winless Northland struggled to hold onto the ball in the first half and gifted Bay of Plenty some good opportunities.
However, the visitors did not make the most of those opportunities, dropping a lot of ball in reply. The Steamers would eventually go into the break 9-0 ahead following another penalty to Evemy.
After a messy and uninspiring first half, the opening try finally came inside the opening two minutes of the second half.
Substitute Dan Hollinshead almost scored for the Steamers following a lovely play down the right side, before team mate Elijah Nicholas scored out wide on the left a few phases later.
Northland crossed for the next try after wisely declining a penalty goal close to the sticks. They kept the pressure on and were rewarded when Daniel Hawkins ducked under a tackle and scored from close to the tryline.
Things got worse for the Steamers when halfback Jono Kitto was sent to the sin bin close to the 60-minute mark.
But despite the advantage, Northland would concede the next try.
Steamers substitute Joseph Royal was held up over the tryline and the Bay were awarded a penalty try the following play, as their scrum was brought down illegally close to the tryline.
The Steamers then turned on some class scoring perhaps their best try of the season.
Hollinshead made a lovely cross field kick which was snapped up by a flying Tino Nemani. Nemani slipped a pass to Chase Tiatia who ran deep into the Northland 22m zone. A few lovely passes later and Lalakai Foketi crossed in the corner.
The Bay chased a four-try bonus point and got it, despite having Joe Tupe shown a yellow card in the last five minutes.
In the last minute of the game Keepa Mewett charged over to secure the bonus point.
Northland 5 (Daniel Hawkins try) Bay of Plenty 37 (Elijah Nicholas, penalty try, Lalakai Foketi, Keepa Mewett tries; Nick Evemy 3 pen, Dan Hollinshead 4 con) HT: 0-9.