If you decide not to go ahead with the main story when you are taking the boat to Durlin’s office, you will likely head off and take part in the side quest for the slag chimneys in the surrounding lake. There are three of them to shut down and you will come across a Nornir chest when working your way through the three of them.
This Nornir chest has two braziers that are quite easy to light and a third one that is nowhere to be found. It will take quite a bit of digging around the area here to figure out where the final brazier is.
You will need to jump across the small gap in the wooden platform to the right side of the Nornir chest. If you walk forward, you will spot two wooden barrels next to a fence. Both of these barrels have a green metal shield on them. If you shoot this with a stun arrow, it will destroy the barrel, revealing a hole in the fence behind it. The last brazier can be found here.
If you are unsure where to go or where to find any of the other braziers for this Nornir chest, check out the video guide below.