The Resynced AtlasCaptain's field guide

"AC Black Flag Resynced San Juan Treasure Location & Map Solution"

"Find the San Juan buried treasure in AC Black Flag Resynced: Santanillas map origin (189, 220), Diving Bell tunnel route, eel evasion, and Ultimate Fire Barrel Strength plan."

AC Black Flag Resynced San Juan Smuggler's Den and buried treasure chest

The San Juan buried treasure is one of the most frequently searched treasure map solutions in Assassin's Creed Black Flag Resynced. Unlike surface-level island chests, this treasure is buried deep inside an underwater Smuggler's Den that requires the Diving Bell to enter.

Digging up this chest rewards 3,000 Reales and the Ultimate Fire Barrel Strength Plan (required to max out your Jackdaw fire barrels).

San Juan Treasure Quick Reference

Attribute Detail
Treasure Map Origin Santanillas (189, 220) — Looted from a skeleton on the northeastern beach
Dig Site Location San Juan (455, 462) — Inside the submerged Smuggler's Den
Key Requirement Diving Bell (Unlocked in Sequence 6, Memory 1: Diving for Medicines)
Rewards 3,000 Reales + Ultimate Fire Barrel Strength Plan
Harbormaster Upgrade Cost 8,000 Reales

Step 1: Obtain the Map at Santanillas (189, 220)

Before sailing to San Juan, you must obtain the matching treasure map, or the dig prompt will not appear:

  1. Fast travel or sail to Santanillas (189, 220) in the western sea.
  2. Head to the northeastern shoreline near the Spanish ruins.
  3. Locate the dead explorer skeleton resting against the rocks.
  4. Loot the body to acquire Treasure Map (189, 220 → 455, 462). The sketch depicts the subterranean entrance to San Juan with an "X" mark inside the cave tunnel.

Step 2: Navigate the San Juan Underwater Tunnel

flowchart TD
    A[Deploy Diving Bell at San Juan 455, 462] --> B[Swim North into Submerged Rock Arch]
    B --> C[Pass First Air Pocket / Barrel]
    C --> D[Evade Moray Eels in the Narrow Rift]
    D --> E[Avoid Jellyfish Cluster in Cavern Shaft]
    E --> F[Surface Inside Smuggler's Den]
  1. Sail to San Juan (455, 462) in the Jagua sector and interact with the diving zone.
  2. Descend with the Diving Bell.
  3. Swim northeast into the illuminated underwater archway.
  4. Moray Eel Hazard: Moray eels hide in wall crevices along the narrow shaft. Hug the opposite wall and swim steadily to avoid their bite attack.
  5. Take a breath at the wooden air barrel halfway through the tunnel.
  6. Swim upward through the vertical rock chimney into the hidden cave pool and surface.

Step 3: Clear the Guards & Dig the Chest

  1. Climb out of the water onto the wooden docks of the Smuggler's Den.
  2. Stealth Neutralization: Smuggler guards patrol the cavern docks. Use whistle assassinations from corner cover or sleep darts to neutralize them quietly.
  3. Walk past the campfire into the central tunnel leading toward the back ladder.
  4. Look for the fragile wooden planks / barricade on the right-hand wall.
  5. Break through the wooden planks (or walk behind the scaffold crates).
  6. Approach the dirt patch between the two torch sconces—the "Dig" prompt will appear.
  7. Open the chest to claim 3,000 Reales and the Ultimate Fire Barrel Strength Plan!

Upgrading Fire Barrel Strength

After retrieving the plan, dock at any major town or speak to the Harbormaster at Great Inagua:

  • Navigate to Jackdaw Upgrades → Secondary Weapons → Fire Barrels.
  • Purchase the final tier for 8,000 Reales (How to Make Money Fast).
  • Combat Effect: Enhances the explosive detonation damage of dropped fire barrels, making them highly effective against pursuing enemy vessels and boss encounters (Legendary Ships Guide).

Sources & Evidence

Related Guides: All 22 Treasure Maps & Dig Locations | All 12 Ultimate Plans Directory | How to Make Money Fast | Legendary Ships Boss Guide | All 18 Outfits & Armor