It is in Northport, about 66 steps west of the spot the map marks with that name.

And 8 down from the surface once you are there.

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

• A rope. You drop in through a trapdoor, and a rope is how you climb back out.
• Something for demon, warlock and giant spider — they live down there.

The chest is 8 floors under the surface. Going down over it, this is what each floor uses:

1. Ground: down through a ladder.
2. 1 down: down through a ladder.
3. 3 down: down through a trapdoor.
4. 4 down: down through a trapdoor.
5. 5 down: down through a ladder.
6. 6 down: down through a ladder.
7. 7 down: down through stairs.

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

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

• 3 — a trapdoor, 3 down
• → — the treasure lies this way

• 4 — a trapdoor, 4 down
• → — the treasure lies this way

• 5 — a ladder, 5 down
• → — the treasure lies this way

• 6 — a ladder, 6 down
• → — the treasure lies this way

• 7 — stairs, 7 down
• → — the treasure lies this way

Some floors are not on the list: their way down is further off than the rest, and that stretch you have to find yourself.

• 1-2 — the chests
• 3 — the chest

There are 3 chests here under 3 quest numbers, so you can take them all.