Mine Layers — Layer 1/2/3 Mechanics & Loot Tables

Updated May 25, 2026 · 7 min read · Full yield reference

The Mine in Blue Prince is the only multi-layer room in the mansion. Drafting the Mine drops you into Layer 1 — a generally safe vein-mining sandbox — but Layer 2 sits below it (Aquarius pipe puzzle gates the ladder) and Layer 3 sits below that (Pump Room PSI puzzle gates a chute). Each layer has its own yield curve, hazards, and Lantern requirements. This page is the complete reference.

Mine Cross-Section

Layer 1 — Entry Vein

The default layer. Drafting the Mine drops you here.

• Lighting: Fully lit. No Lantern needed.
• Access cost: One Pickaxe charge per vein, 3 charges per Mine draft.
• Average yield: 2 Gems per visit. Occasionally 1 Coin from a side seam.
• Hazards: None. Layer 1 is the safe layer.

If you have no Pickaxe, the Mine is still useful — Layer 1 has one free Gem at the entrance, no charge required.

Layer 2 — Aquarius Floor

Reached by solving the Aquarius pipe puzzle on Layer 1's south wall. See the Aquarius Pipes guide for the 11-pipe layout.

• Lighting: Wall sconces. Visibility is fine but darker than Layer 1.
• Access cost: Solve Aquarius once per save. After the first solve, the ladder stays open on every future Mine draft.
• Average yield: 4 Gems per visit, plus one Iron ingot per draft (used in the Crown route — see Crown guide).
• Hazards: Water pooling. Standing in a flooded tile for two ticks consumes one Step.

Layer 3 — The Dark Vein

Reached by solving the Pump Room PSI puzzle, which opens a chute on Layer 2's east wall. See the Pump Room guide for the lever and dial sequence.

• Lighting: Pitch dark. A Lantern is mandatory.
• Access cost: Pump Room PSI must be solved every run (it does not stay open like Aquarius).
• Average yield: 6 Gems per visit, plus a guaranteed Sapphire Eye on the first clear of every save file.
• Hazards: Drop pits. Without a Lantern, the first step puts you in a pit; the next morning resurrects you in the entrance hall with all run gems lost.

The Sapphire Eye is one of the four Crown of Mt. Holly artifacts. After picking it up once, Layer 3 still yields 6 Gems per visit but no more Sapphire Eyes.

Where to Get a Lantern

Lanterns drop from three sources:

1. Pawn Shop. 12 Coins. Common stock — appears about 60% of Pawn drafts.
2. Apothecary. 3 Gems + 1 Honey vial. Mid-cost but no Coin requirement.
3. Cellar drop. Random 4% chance per Cellar draft. Don't bank on it.

The Lantern is single-use for the dark Layer 3 only. After you climb back up, it's gone.

Reset Rules

What persists across in-game days:

• Layer 2 access (Aquarius solved): persists per save
• Sapphire Eye: persists per save (one-time pickup)
• Pump Room PSI solve: resets every day — must re-solve to reach Layer 3
• Mine layout (vein positions): randomized per Mine draft

Optimal Farming Strategy

For a Day-5-or-later run with the Crown in mind:

1. Draft the Mine. Walk Layer 1 — pick up the free Gem.
2. Descend to Layer 2 (Aquarius already solved). Collect 4 Gems + Iron ingot.
3. If you have a Lantern, run the Pump Room PSI in a side draft, then descend to Layer 3 for 6 more Gems.
4. Climb out. Total: 11 Gems and an Iron ingot in one Mine draft.

That's roughly the Coin value of three Pawn-Shop sells, so a Day-5+ Mine draft is the highest-EV single draft in the game.

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