At the top of the cliff, above and behind the stone heads, was an altar and the entrance to a cave of unknown depth. The altar was carved with bizarre sea life and odd-looking ocean vessels.
The tunnel behind the alter was connected with a domed chamber, in turn connected to a series of tunnels that led to an underground sarrukh laboratory. This laboratory was connected by portals with similar places in Ilimar and Okoth.
Chalsoné was built by the sarrukh in the ancient past.
Around 1479 DR, the sarrukh were using this ancient laboratory once again. Because of their experiments many pirate ships were lost in the vicinity, and eventually the pirates began to avoid the place altogether.