Sea Forts

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Disambig.png This article is about the stone Phantom fort introduced in Season Six. For the Skeleton fort World Event location, see Fortress.
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Battle phantoms and claim your share of the treasure that awaits within the treasury!

Sea Forts are built-up, fortified stone structures in the ocean. When active, players can take on waves of Phantoms and a Captain of the Fortress to reveal a stash of treasure.

List of Sea Forts

There are six individual Sea Forts around the Sea of Thieves, two in each region except The Devil's Roar.

Sea Forts in each region come with a unique theme for their region. The Shores of Plenty has a standard Spanish fort style, The Wilds has a chained-down prison theme, while forts in The Ancient Isles are ruined and overgrown with flora.

Sea Fort Grid Region
Royal Crest Fortress J-6 The Shores of Plenty The Shores of Plenty
Imperial Crown Fortress B-11 The Shores of Plenty The Shores of Plenty
Ancient Gold Fortress F-19 The Ancient Isles The Ancient Isles
Old Brinestone Fortress K-21 The Ancient Isles The Ancient Isles
Traitor's Fate Fortress S-6 The Wilds The Wilds
Mercy's End Fortress P-14 The Wilds The Wilds

The Location

The interior of a sea fort is split up into multiple different rooms of different uses to the previous inhabitants. These include a rowboat docking bay, living and food preparation spaces, sleeping quarters, and defence posts.

Sea Forts accommodate many interactive mechanics and points of interest:

  • 1 Treasury Vault on the lower level
  • 1 Store Room on the roof level
  • 1 Jail Cell on the lower level
  • Miniature Cannons (Functionally equivalent to the Cannon mounted on Cannon Rowboats)
  • Special containers, which may be opened to occasionally reveal small treasure items or Gold Pouches
    • Large Crates with removable lids
    • Small Foot-chests
    • Small Wall-mounted cupboards
    • Large Floor-mounted cupboards with two doors
    • Large Vanities with two doors
  • Floor-mounted hatches, and wall-mounted window shutters.
  • Pulley systems for controlling a platform, some barrel lifts, and portcullis gates.
  • Chairs
  • Bunk Beds
  • 1 Wall mounted Map Table in the Kitchen
  • 1 large Stove able to cook four items at once
  • 1 warning Bell on the roof level
  • Multiple Barrels with varying supplies.

The Raid

Unlike other World Events, Sea Forts are always active provided that they have not recently been completed by a crew. An active Sea Fort is indicated by the raised flag, ghostly lights and ominous music on approach. Upon approaching the Sea Fort, stationary cannons will begin firing at oncoming ships in an attempt to fend off attackers. Sea Forts will repopulate when no player crews are occupying the area within approximately two tiles on the Map Table.

Upon arriving at the Sea Fort, players will fight 8 short waves of Phantoms. The sound of a deep Bell ringing can be heard to indicate the start of a new wave.

Sea Fort Phantoms slightly differ from the standard Phantom; they have only 55 health rather than the regular 100 and can have clothing and armor that resembles soldiers in the Spanish Armada. Like other Phantoms, Sea Fort Phantoms can drop Ammo Pouches on defeat.

The final wave will consist of a small number of Phantoms and one Captain of the Fortress. Upon defeat, the Captain of the Fortress will drop a Fortress Treasury Key and all remaining Phantoms will retreat. This key can be used to unlock the Treasury Vault at the bottom floor of the Sea Fort, revealing a stash of Ghostly and Regular Treasure for the taking.

Additional Treasure Items can be found throughout Sea Forts by searching the interactive cupboards and shelves around the Fort. A second, smaller treasure room on the top floor of each Sea Fort can be unlocked with a Fortress Store Room Key found hidden somewhere within the Fort.

Once a raid is completed, players are free to remain within the area for as long as they like. Cleared Sea Forts will not repopulate until all crews have left the area around the Sea Fort.

Some aspects of Sea Fort encounters are balanced to the number of players in the attacking crew:

One Player Crew Two Player Crew Three Player Crew Four Player Crew
Number of waves 8 8 8 8
Phantoms per wave 3-4 4-5
Phantom health 55 55 55 55
Captain of the Fortress health 250 350 550


There are three different ways to earn treasure in a Sea Fort: Treasury Vault, Store Room and Hidden Stashes. All the Sea Fort's treasure is worth between 15,000 and 25,000 Gold (without Emissary).

Treasury Vault

Sea Fort treasure room.png

The Treasury Vault contains the bulk of the fort's treasure. It is unlocked by defeating each wave of Phantoms and using the Fortress Treasury Key dropped by the Captain of the Fortress on the final wave to unlock the door on the lower level of the fort. Opening enough of these Treasuries can achieve players the What's Yours Is Mine and Repeat Offender Commendations.

The contents of the Treasury Vault are guaranteed:

Store Room

The Fortress Store Room is on the roof level and contains a small quantity of valuable treasure. It can be unlocked at any time throughout the battle, providing crews can locate the Fortress Store Room Key by rifling through interactive cupboards and shelves around the fort and inserting it into the door on the roof level. A floor hatch can be opened in here to help players transport treasure out of the room more quickly by dropping it down a floor.

The contents of the Store Room are guaranteed:

Hidden Stashes

Various small treasure items such as Artefacts and Bounty Skulls can be found at any time throughout the battle by rifling through interactive cupboards and shelves around the fort. Finding enough of these treasures can achieve players the Light Fingered and Master Burglar Commendations.

Other Treasure

A number of Gunpowder Barrels as well as 1-2 empty container Treasure Chests can be found scattered around the fort.


Sea Forts Commendations can be found within the Bilge Rats section of the Reputation tab in the Pirate Log.

Scoping the Joints emblem.png
Scoping the JointsVisit all Sea Forts across the Sea of Thieves+30 Doubloons
From Whence They Came emblem.png
From Whence They CameDefeat 250 Sea Fort Phantoms.
  • Grade I: 25
  • Grade II: 50
  • Grade III: 100
  • Grade IV: 175
  • Grade V: 250
Lock icon.png Unlocks the From Whence They Came achievement.
Spectral Slayer emblem.png
Spectral SlayerDefeat a Sea Fort Phantom Captain.+20 Doubloons
What's Yours Is Mine emblem.png
What's Yours Is MineOpen a Sea Fort Treasury.+20 Doubloons
Lock icon.png Unlocks the What's Yours Is Mine achievement.
Repeat Offender emblem.png
Repeat OffenderOpened 50 Sea Fort Treasuries
  • Grade I: 5
  • Grade II: 10
  • Grade III: 15
  • Grade IV: 25
  • Grade V: 50
+50 Doubloons
Light Fingered emblem.png
Light FingeredDiscover secret stashed treasure on a Sea Fort.+20 Doubloons
Master Burglar emblem.png
Master BurglarDiscover 100 secret stashed treasures on a Sea Fort.
  • Grade I: 5
  • Grade II: 15
  • Grade III: 25
  • Grade IV: 50
  • Grade V: 100
Lock icon.png Unlocks the Master Burglar achievement.
Faster Chef emblem.png
Faster ChefCook a meal using all Sea Fort pans at the same time.+10 Doubloons
Fort-y Winks emblem.png
Fort-y WinksShare a bunk bed with another pirate.+10 Doubloons
Get Off My Lawn! emblem.png
Get Off My Lawn!Hit another crew's ship with a Sea Fort Cannon.+10 Doubloons

Ghostly visions

Ghostly visions of Sea Forts began appearing on the seas on March 3rd during 2.4.2. They could only be spotted from a certain distance away so if you strayed too close or far away, the phenomenon would begin to disappear. There were six apparitions visible at specific points around the Sea of Thieves. These visions were removed with the full introduction of Sea Forts in 2.5.0.

Ghostly Sea Fort Vision.jpg
Grid Region
E-9 The Shores of Plenty The Shores of Plenty
G-14 The Shores of Plenty The Shores of Plenty
E-20 The Ancient Isles The Ancient Isles
L-21 The Ancient Isles The Ancient Isles
S-6 The Wilds The Wilds
M-13 The Wilds The Wilds


Sea forts were originally created from the memories of those who dwell within the Sea of the Damned and had no physical form. Following the events of Shrouded Islands and the defeat of the Soulflame Captain, the connection between the world of the living and the world of the dead was strengthened enough for Captain Flameheart to fully manifest these forts with the Sea of Thieves.

The Phantoms that man these forts are loyal to Flameheart, acting as his Jailers to confine living prisoners, most notably the members of Golden Sands Outpost who went missing during the events of Shrouded Islands. These prisoners were rescued during the Forts of the Forgotten adventure.



  • Sea Forts were first announced during the Sea of Thieves 2022 Preview Event.
  • From March 3rd, 2022 to the release of 2.5.0, there were six ghostly visions of Sea Forts around the Sea of Thieves.
  • Sea Fort Bells play the normal bell sound effects when shot or attacked instead of playing the unique sound effect.
  • Sea Forts were created from the memories of pirates, and thus are similar in appearance to famous fortresses from beyond the Sea of Thieves[1].
  • During the Return of the Damned Adventure, a brazier could be found next to the staircase on the top floor containing a Flames of Fate. Each Sea Fort contained a different color. The brazier was removed when the Adventure ended.


  • Occasionally the door opened by the Fortress Store Room Key will be permanently locked, with the appearance of the key already in the door. This will render the Fortress Store Room Key unusable and the loot inside unobtainable.

Patch history

  • 2.6.0 (August 4, 2022)
    • Players can no longer intersect with the archway near Sea Fort Treasury rooms, causing them to see through the environment.
    • Movement around the pillars near the Sea Fort storeroom should no longer feel restricted.
  • 2.5.3 (June 26, 2022)
    • Players should no longer be able to walk through pillars next to the Storeroom in Sea Forts.
  • 2.5.1 (April 7, 2022)
    • The map in the living quarters now displays ships flying the Reaper's Mark Flag in addition to Reaper's Bones Emissaries.
    • The jail cells no longer have a door and there are no longer Golden Sands NPCs in the cells.
    • Inactive Sea Forts no longer show a raised flag.
    • Players using the Sea Fort barrel winches should no longer experience camera stutter when rotating mechanisms.
    • The Treasury door now sits correctly on its hinges.
    • Players can no longer walk up the Sea Fort walls in some locations.
    • Detaching from Sea Fort cannons should no longer cause players to safe teleport.
    • Players should no longer be able to find a way into the dock pillars inside the Fort and move inside the geometry.
  • (March 24, 2022)
    • There are now Golden Sands NPCs in the jail cell.
    • Players fighting Phantoms and performing actions on the lower floor of the Sea Forts should no longer hear those audio effects on the floor above them.
  • 2.5.0 (March 10, 2022)
    • Introduced.
  • 2.4.2 (February 10, 2022)
    • (March 3rd) Ghostly visions of Sea Forts appearing on the seas.

External links


  1. #TriviaTuesday. Sea of Thieves Twitter, April 5, 2022.
  2. #TriviaTuesday. Sea of Thieves Twitter, June 21, 2022.

fr:Forteresse marine