|This article is about the World Event. For the Location, see Fortress.|
A Skeleton Fort (also called Skull Fort after the cloud) is one of the possible World Events in Sea of Thieves, indicated by a large gray Cloud in the shape of a Skull. An active Skeleton Fort can appear at any Fortress Island (apart from Fort of the Damned, which has its own Raid event).
The World Event
While normally dormant, a single Fortress on a server will occasionally appear with a large Skull Cloud hovering above it, visible from a distance. This indicates that the Fortress under the cloud has been invaded by a host of Skeletons who have decided to stash their Stronghold Treasure in the Fortress Vault. The size of the cloud determines its distance from a Player's Crew. The Fort of the Damned Raid encounter also has a Skeleton Skull Cloud, but it differs from a regular fort skull through its size and massive red eyes.
As only one World Event can be active at a time, a Skeleton Fort can only appear if there is no other large markers present in the skies, but there will always be an active World Event in each server. Between every World Event, one Ship on the open seas will get attacked by a Kraken. This also makes it usual for the Crew who cleared the last active Fort to be the first one to get attacked by the Kraken.
When left alone, an activated Skeleton Fort will dissipate in around 30 minutes, allowing for other World Events to cycle in. If an active Fort is approached, its timer will be reset, allowing for it to stay in the world for a longer time.
Approaching the Island
When an active Fort is approached, ominous music will start playing with all of the Fortresses Cannon fortifications becoming manned by Skeletons who intend to sink any Ships coming close to the Island. Once close enough to the Fort and outside the range of any Cannons, the player crew can attempt to raid the Fortress itself. This is done by taking on waves of Skeletons who are trying to defend the Vault at any costs. These Skeleton waves can be of any Skeleton type (Regular Skeleton, Plant Skeleton, Gold Skeleton, Shadow Skeleton) and be armed with all Weapons except the Eye of Reach.
The Skeleton Fort Event
Once on the Island, players can take on the Fort event itself.
Each Active Fort has 12 waves of 10 Skeletons before the first Skeleton Captain is summoned at the central Fort structure. There are two types of Skull Forts: Forts that only spawn regular clothed Skeletons, or Forts that can spawn any type of Skeletons. No matter the type of the Fort, the Skeletons can usually only equip up to 2 Weapons of the following: Hands, Cutlasses, Pistols, Blunderbusses. In some Forts, around 1-3 Gunpowder Skeletons can appear as additional enemies. No matter the Fortress type, all Skeletons of these waves will have 100 Health (4 Cutlass swings or a point-blank Blunderbuss shot). The type of Fort spawns that players get do not seem to be tied to Crew size or Region. A wave is counted complete once all the wave's Skeletons have been defeated.
Note that aside from clothed wave Skeletons, Forts usually also spawn a handful of regular, white Skeletons with 100 Health. These Skeletons are not tied to the waves and usually man the Cannons and protect the shores of the Island. They will despawn when all Players have been sent to the Ferry of the Damned, allowing the Island to soft-reset.
First Captain Wave
After the 12 regular waves of Skeletons have been dealt with, the first Boss wave will appear with another wave of 10 Skeletons and a Skeleton Captain. The Skeleton Captain type is usually dependent on the type of Skeleton wave it spawns with. Skeleton Captains can carry the same Weapons as regular Fort Skeletons (except the Gunpowder Barrel). These Skeleton Captains have 600 Health and drop a Villainous Bounty Skull upon defeat.
Second Captain Wave
After the first Skeleton Captain wave has been defeated, the second boss wave will appear with yet some more Skeletons, but this time accompanied by two Ashen Skeleton Captains: An Ashen Key Master and an Ashen Guardian. These Captains are mechanically identical to the first wave's captain, with the main difference coming down to their Ashen Skeleton appearance.
Skeleton Lord Wave
After the second Captain wave is completed, the final Skeleton Lord wave will commence. Aside from another group of Skeletons, one of the three fort Skeleton Lords can appear: The Mutinous Helmsman, The Two-Faced Scoundrel or The Duchess. The three lords are mechanically identical, having around 4000-4500 Health.
These Lords can switch between a Cutlass, Flintlock and Blunderbuss depending on their distance from Players. They can also summon more Skeletons (around 10 regular weak Skeletons with 50 Health), burrow into the ground and reappear elsewhere, and create a massive Shockwave, pushing any Pirates back and dealing damage to them the closer they are to them.
Players will know that the Lords are getting low on health when they start eating Bananas. This is just an animation and does not actually increase the Lord's health.
Once the Skeleton Lord is defeated, they will drop a Stronghold Key and an additional Stronghold Skull and Skeleton's Orders. The Orders give the crew an X Marks the Spot Map with 1 X that uncovers a Rag & Bone Crate. After the Lord is dead, the Skull cloud will dissipate, marking the end of the Skeleton Fort.
The final Skeleton Lord will drop the Stronghold Key, which can be used to open the locked Fortress Vault below the main Fort structure. The Fortress Vault contains a large amount of loot with a guaranteed Stronghold level item of each type.
The Fortress Vault of an active Skeleton Fort will become locked until the Skeleton Lord is defeated and a Vault Key is acquired. The entire Skeleton Fort event will give a large amount of Treasure, worth between 25,000 and 45,000 Gold (without Emissary).
The following Treasure is rewarded for completing a Skeleton Fort World Event:
- 3 guaranteed Villainous Bounty Skulls, dropped by the three bosses: Skeleton Captain, Ashen Key Master and Ashen Guardian
- 1 guaranteed Ashen Key, dropped by the Ashen Key Master
- 1 guaranteed Skeleton's Orders Treasure Map, dropped by the Ashen Guardian that unearths an Ashen Chest on the Fort.
- 1 guaranteed Stronghold Skull, dropped by the Skeleton Lord
- 1 guaranteed Skeleton's Orders Treasure Map dropped by the Skeleton Lord that unearths a Rag and Bone Crate
- 1-2 Stronghold Chest
- 1-2 Stronghold Skull
- 1-2 Crate of Ancient Bone Dust
- 1 Stronghold Gunpowder Barrel
- 2-4 Gunpowder Barrels
- 1 Ashen Chest
- 1-2 Gift
- 1-2 Mermaid Gem
- Around 15 random regular Treasure items including: Treasure Chests, Artefacts, Bounty Skulls, Trade Good Crates & filled Collector's Chests
- 1 Chest of Rage (only in Molten Sands Fortress)
There is no way to open the Stronghold Vault without the Stronghold Key. While the Key may be used to open other Stronghold Vaults, typically only the Vault of the Fortress that was completed or currently active will contain any Treasure.
Molten Sands Fortress
All Skeleton Fort events are virtually the same, with the exception of an active Fort at the Molten Sands Fortress in the Devil's Roar, which has an active Volcano that can make things more difficult. The main differences of this Fort over the others is that the Skeleton Waves may spawn a wave of Ashen Skeletons who are resistant to Fire damage, the Treasure rewarded by the Skeleton's Orders map dropped by the Skeleton Lord Boss and a guaranteed Chest of Rage and Ashen versions of regular Treasure in the Fortress Vault. The Fortress Vault at Molten Sands Fortress has a heightened chance of containing two gifts.
- The eyes of the Skull Cloud are not an indicator for the difficulty or other ships near the fort.
- Skeleton Fort events can be defeated solo with enough time, skill and patience, however it is recommended to take these Events on with other people.
- Some Forts have fairly sparse floorboards covering the Vault itself, allowing players to take a sneak peek at the loot inside. Note that while you can see Gunpowder Barrels through these holes, you can not make them blow up by shooting through the floorboards, despite getting hit markers on a hit.
- A completed Skeleton Fort event will give a large amount of Emissary Grade Reputation to any Emissary Ships in the Fort's range (does not work for Reaper's Bones Emissaries)
- It takes 15 Gunpowder Barrels to kill a Fort Skeleton Lord.
- Be mindful of your surroundings when tackling an active Skeleton Fort, as the high rewards make the Event a hotspot for Player versus Player combat. Likewise, if you see a Ship on an active Fortress, you can wait for them to clear the Fort and attack them once the fortifications are unmanned and they are busy transporting their loot.
- Aside from the Skeletons who will man any Cannons that are in range of any approaching Ships, your own crewmates can also make use of these Cannons to keep any other Ships away from the Fort. Ideally, one player may remain on the ship to keep watch for rival crews.
- The large number of Gunpowder Barrels on a Fortress make them a good tool for dispatching entire waves of Skeletons (these are especially useful against more durable enemies), however these can also be used to blow up any approaching enemy Ships, or even used against the bosses of the Fort. Watch out, as these can also be used against your own ship!
- The inclusion of Firebombs make completing Forts an absolute breeze. If you lure all the Skeletons to one place, you can throw a Firebomb at them and they will die within seconds no matter their Type. Firebombs are also effective against the Skeleton Captains and Skeleton Lord for additional damage.
- If you can lure the Skeleton Lord on the beach or a visible spot, you can position your ships Cannons towards the Lord and kill them with Cannonballs. It should take around 40-45 Cannonballs to kill a Skeleton Lord.
- Take great care when battling the Skeleton Lord at close range, as their Blunderbuss' damage is capable of killing an unwary player, in a single hit. Juggle between mid to close range to avoid heavy damage.
- Sometimes Rowboats spawn on a Fort. Although they usually spawn behind the fort walls and get stuck, their Chests still contain a lot of Resource items.
- Note that all Green Cursed Cannonballs effect the Skeletons, Captains and Lords of the Fort and can also be used as a tool against them.
- When you have finished a Fort and are looting the vault, make use of the Ship Harpoons to make transporting Treasure easier. Try parking your Ship closer to the Vault. Many Forts also spawn a Rowboat to help with Treasure transport.
- The Fortress Vault will stay locked as long as its Vault Key is within the World. Clever pirates who are under attack when finishing a fort can hide the Key on their boat or on the Fort itself and come back for it later.
- Early in the game's release, Forts would originally spawn every 3 hours.
- During the month of the Crews of Rage (Content Update), which introduced the Chest of Rage, the Molten Sands Fortress was the only active Skeleton Fort.
- During the months of the Ashen Treasures Bilge Rat Adventures, all Skeleton Fort clouds appeared completely red.
- All of the Skeleton Forts were built and manned by Captain Grimm and his troops, constructed under direct orders of Captain Flameheart. After Flameheart's fall, Skeletons continued to store riches as tribute to their pirate king should he ever return. 
- Gunpowder Plot → Destroy 5 Skeletons at the same time by Shooting a Gunpowder Skeleton on an active Fort; while at least 1 other Crew is on the Island at the same time. | 20
- Legendary Gunpowder Plot → Destroy 5 Skeletons at the same time by Shooting a Gunpowder Skeleton on an active Fort; while at least 1 other Crew is on the Island at the same time. (20 times) | 20
- Master of Black Powder → Sell 10 Stronghold Gunpowder Barrels | 20
- Golden Master of Strongholds → Sell 10 Stronghold Chests | 20
- Mystical Master of Strongholds → Sell 10 Stronghold Skulls | 20
- Master of Ancient Bone Dust → Sell 10 Crates of Ancient Bone Dust | 20
- Helmsman Hunted → Defeat The Mutinous Helmsman. | 10
- Mutiny Crushed → Defeat The Mutinous Helmsman 10 times. | 20
- Tied to the Wheel → Defeat The Mutinous Helmsman 25 times. | 30
- Scoundrel Slain → Defeat The Two-Faced Scoundrel. | 10
- Two Faces, One Fate → Defeat The Two-Faced Scoundrel 10 times. | 20
- Facing the Inevitable → Defeat The Two-Faced Scoundrel 25 times. | 30
- Duchess Destroyed → Defeat The Duchess. | 10
- Duchess of Death → Defeat The Duchess 10 times. | 20
- A Noble Defeat → Defeat The Duchess 25 times. | 30
The Red Skeleton Fortress Cloud during the Ashen Treasures Bilge Rat Adventures
The Mutinous Helmsman Skeleton Lord
The Two-Faced Scoundrel Skeleton Lord
The Duchess Skeleton Lord
- Sea of Thieves Official Twitter #TriviaTuesday posted January 28, 2020.