It appears this must be the main chamber of the entire tomb complex, and I must say, it's quite disappointing—there are barely any traces of burial goods on the circular platform below. In other words, they were likely going to leave empty-handed this time.
The main chamber is located right in the middle of the circular cave, connected to the opposite stone wall of the entrance platform; a zigzagging path leads down to the platform, and around it, there's a shimmer of water. If my guess is correct, it must be an underground lake lower than the platform engulfing it.
Although the cave is still very cold, the lake has not frozen over; droplets of water fall from above the cave from time to time, ticking as they hit the surface of the lake.
