Underground Network is the quest chain that unlocks the Hidden Smuggler Base in Windrose. It takes the player from Tortuga to a Foothills Smuggler Camp to the Smugglers Waters archipelago and finally into the Smuggler cave.
How to Start
Underground Network becomes available after reaching Tortuga through the main story. Triggering the quest requires the player to find and clear a Smuggler Camp somewhere in the Foothills (marked as a coastal Pirate Camp on the map). One of the camp's chests contains a Letter to a Good Friend, which is the keystone lore item.
Reading the Letter
The Letter to a Good Friend hints at a Smuggler operation hidden in the Smugglers Waters zone of the world map (marked by green-striped water). The letter points the player toward a specific island within that zone, where a cave entrance can be found along the coast. The Curios Tab stores the letter for re-reading during travel.
Reaching the Smuggler Cave
The Smugglers Waters island chain is a significant sailing trip from Tortuga. Bring naval supplies, a fully provisioned ship, and boarding gear in case of encounters along the way. The cave entrance itself is not combat-heavy; the Smuggler faction is neutral until the player becomes hostile.
Inside the Cave
The Smuggler cave contains Smuggler-aligned guards and a small dungeon layout. Clearing the guards triggers the quest's next objective: refit a Ketch on the beach outside the cave. Refitting the Ketch unlocks persistent fast-travel to the Hidden Smuggler Base and spawns the key NPCs: the Smuggler Buyer (next to Marita), the Smuggler Bounty Agent, and the Smuggler Provisioner.
Quest Rewards
Permanent fast-travel to the Hidden Smuggler Base
Access to the Smuggler Buyer (the only luxury/contraband sink in the game)
Access to the Smuggler Bounty Agent and Provisioner inventory
Unlocks the Smuggler faction reputation grind
See Also
Hidden Smuggler Base — the location this quest unlocks
Smugglers of Port Royal — faction overview
Tortuga — quest starting hub
Curios Tab — where the Letter to a Good Friend is stored