On the rough path leading toward Sleeping Tree Camp is a group of standing stones and three Nordic Puzzle Pillars. Next to the puzzle is a closed grate on top of a caved-in ruin. Solving the puzzle and activating the handle unlocks and opens the grate allowing access down the spiral staircase to a skeleton and a chest.
The correct puzzle pillar positions can be found on the back of the stones the pillars are standing in front of. One symbol is still attached to its stone, the other two have fallen onto the ground. The correct selections are Whale, Eagle, Snake (from left to right if standing by the lever, as shown in the picture). After rotating the symbols, activate a handle to finally open the grate. Be sure that the symbol selected is lined up with the arrow at the pillar's base (towards the handle).
- As of the 1.8 update, and installation of Dawnguard, Hearthfire, and Dragonborn, the chest has proven to be safe. Items were stored there for three to four in-game months before update, and were still safe afterwards. A Hypothetical Treachery will respawn if taken, but this does not appear to affect stored items.