• A rope. You drop in through a hole, and a rope is how you climb back out.
• Something for beholder, slime and orc shaman — 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 a hole.
2. 1 down: down through a hole.

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

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

• 1 — the chest

One chest, one reward.