During your exploration in Chasm, you might stumbleupon with Treasure Map Fragment in 2 different treasure hoarder camp: one in Chasm surface, and the other one in Chasm underground.
This 2 map fragment can be combined as 1 treasure map which show location of Treasure Hoarder secret tunnel that will bring you to their secret stash underground.
Question is, where’s the map fragments location and how to fin treasure hoarder secret stash?
Treasure Map Fragment 1 – Chasm Surface
First fragment can be found at Treasure Hoarder Camp southeast of Lumberpick Valley. This location is actually part of another quest: Undetected Infiltration where you can get quest item called Cup of Commons.
Treasure Map Fragment 2 – Chasm Underground
Second map fragment can be found at treasure hoarder camp northeast of Ad-Hoc Main Tunnel teleport waypoint.
Treasure Hoarder Secret Tunnel Location
Then, both fragment will become item called Treasure Hoarders Treasure Map which will show it’s exact location, southeast of Tiangong Gorge teleport waypoint.
Destroy bomb crate in this camp to burn blanket covering secret entrace to the tunnel.
After that, you can enter and claim your rewards: 1 Exquisite Chest, 1 Precious Chest, and 1 Lumenstone. Upon opening this stash, you will also get achievement: Den of Thieves.