It is in Thais, about 74 steps south-west of the spot the map marks with that name.

And 2 down from the surface once you are there.

• 1 — Thais, as the map itself names it
• 2 — the ground above the treasure

• Key 20: a locked door bars the way, and that is the number of the key that opens it.
• Key 21: a locked door bars the way, and that is the number of the key that opens it.
• Key 22: a locked door bars the way, and that is the number of the key that opens it.
• Key 23: a locked door bars the way, and that is the number of the key that opens it.
• Key 32: a locked door bars the way, and that is the number of the key that opens it.
• Something for orc warrior, rotworm and orc spearman — they live down there.

The chest is 2 floors under the surface. Going down over it, this is what each floor uses:

1. Ground: down through stairs.
2. 1 down: down through a ladder.

• 1 — the way in: stairs, ground
• → — the treasure lies this way

• 2 — a ladder, 1 down
• → — the treasure lies this way

• 1 — the chest

One chest, one reward.