There are two caves at the Dueling Peaks that form part of the same puzzle. The cave on the north side of the river has a hint of the puzzle’s solution drawn on the ceiling, while the southern cave is where the puzzle itself is.
Anyway, let’s head into the Dueling Peaks South Cave, found on the spot marked in the image above. Its approximate coordinates are 1183, -1942, 0245.
Go into the cave and go straight forward to climb up a wall leading to the puzzle room.
You will find a bunch of pressure plates on the floor and four rocks. The plates form a sort of triangle, with the further row being only 1 plate and the closest one being 5 plates.
We will be referring to the furthest away row as the first, and the closest one as the fourth. Of course, we’ll also use images with highlights to make it easier to read.
Grab one of the rocks with Ultrahand and put it down on the leftmost column of the second row.
Now, grab the rock on the top row and place it on top of the middle column of the third row instead.
Remove the leftmost rock from the third row and put it in the second column from left to right on the fourth row.
Lastly, grab the only rock that’s not on a plate and place it on top of the rightmost column on the fourth row.
In short, put the four rocks in the plates with arrows in this image. This should complete the puzzle, opening a door and revealing a chest with your reward!