This chest is accessible during the journey chapter Chapter 12: Escape from Helheim 1, right before boarding the boat. You’ll have to push a stone block to be able to jump across the gap of the broken bridge.
Rune Seal 1
This is found in the stone pillar near the bridge as shown below. You can also destroy it as soon as you start the chapter from your starting point on the platform above.
Rune Seal 2
Next, burn the bramble inside under the platform to the south to free the stone block. The second rune seal is found inside the hollow center of the stone block itself. Push/pull the stone block so that it lines up with the open gap to the east. Climb over the block and jump behind it to be able to destroy this rune seal.
Rune Seal 3
Climb over the stone block again and pull it all the way to the back this time. This should line it up to the ledge above. Climb up the block and pull yourself up to the next ledge. Loot the wooden chest then look at the yellow pillar to the southeast. You should see the last seal there. Adjust your axe throw and once destroyed, go back down to loot the nornir chest. Once done, backtrack to the main path and board the boat.