I mentioned with previous Nornir chests in God of War Ragnarok that two are easy to find and one is not. The River Delta Nornir chest is a bit of an exception to this where it is actually quite hard to find 2 if not three of them. When you do locate them all, destroying the brambles around one is a challenge all of its own.
The first rune paddle can be seen when you climb up the chain hanging from the platform in the middle of the area. The second can be found if you walk back from where the path to the Nornir chest is, you will make a small jump over some water. Turn around and look to the right and you will see there is a rune paddle rapped in brambles. You will need to burn these away.
The final rune paddle can’t be hit unless you leave the island. If you make your way over to the island behind the river delta where you can find Brock and a gateway portal, you will see the final rune paddle behind a rock facing the water. Hit this and the chest will unlock.
The video guide below will help you out if you are struggling to find the rune paddles for this Nornir Chest.