The Sinkhole is located above The Arena.
- On top, an Obelisk and Harlot's Journal #7 can be found.
- A group of Undead Hyenas and Skeletons roam around.
- Down the sinkhole, in the arena, it holds the Undead Dragon.
- A stone in the back can be interacted with. This will let the player learn recipes for Dragonbone Weapons (you need to have Star Metal Tools unlocked to be able to validate the feat).
The third of the Scouting Mission Notes alludes to some background lore.