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Sea of Thieves Skeleton Forts: Skull Clouds, Stronghold Keys and how to defeat the raids

How to take down one of Sea of Thieves' toughest challenges.

Skeleton Forts, marked by those big, rather ominous-looking skull clouds in the sky, are Sea of Thieves' take on the late-game raid.

They're tricky, publicly-open events - anyone in your instance can sail up and join in - and require a great deal of coordination and planning to take down effectively.

When you do however, you'll likely find a Stronghold Key which unlocks a special store full of ridiculously valuable treasure.

Here in this guide then, we'll take you through an explaination of what Skeleton Forts and those big skull clouds are, how to get the Stronghold Key and, of course, our step-by-step advice on how to assault and defeat Skeleton Forts themselves.

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Skull clouds and Skeleton Forts in Sea of Thieves explained

Those menacing, green-eyed skulls you might have seen hovering up in the clouds already serve on purpose: they tell you that a Skeleton Fort raid is under way.

The Skeleton Forts themselves are essentially publicly-open raids - think Guild Wars, or Destiny's Public Events - and they play out in the following way:

  1. A big skull cloud appears to indicate one has gone live.
  2. Cannons, manned by skeletons, attack as you approach.
  3. Several waves of various enemies attack after you clear out the cannons and land.
  4. A final boss, in the form of a particularly tough Skeleton Captain, appears with the last wave.
  5. The Captain drops a Stronghold Key on defeat, which opens a vault to some outrageously valuable treasure.
  6. You pick up all the treasure, ferry it to your ship as fast as you can, and cheese it!

That's how it unofolds in basic terms, anyway, but if you're seriously thinking of taking one on (and actually want to succeed!) we recommend you read on below for a step-by-step guide.

Cover image for YouTube videoHow to assault a Fort in Sea of Thieves

How to prepare for Skeleton Forts in Sea of Thieves

Here's how to start preparing:

  • Stock up - Before you head over to the Skeleton Fort you need to seriously manage your supplies. Max yourselves and your ship out on Cannonballs, Bananas, and Wooden Planks and make sure all your weapons are fully loaded from the ship's store.
  • Gather a crew - We did it with a crew of three on a galleon, but 4 would certainly make it easier. If you're on a one- or two-person sloop, you'll absolutely need help from another crew in the world.But good luck tracking other crews down without getting killed or betrayed!
  • Set sail - You need to actually get there before you can start it, of course, but in Sea of Thieve's that's often half the battle. The skull cloud is visible from anywhere on the map, so beware it could take you quite some time to reach it.
  • Clear out the defenses - As soon as you arrive at the raid you'll be peppered with cannon fire. As you get closer they'll get significantly more accurate, so divide up roles between you - some firing your own cannons to take out the skeletons' ones, and some repairing the inevitable holes in your ship.
  • Park somewhere smart - You need easy access on and off the island, so preferably aim for a beach with a path leading in-land. Be smart about your ship's positioning - have it turned facing away for a rapid escape, with sails extended and wheel direction ready (and obviously don't forget to actually drop anchor amid all the chaos).
  • Split into two groups - After the enemy cannons are cleared out, get ready to dive in. One raiding party needs to head out on land, and the other needs to defend the ship, ideally with two people in each party. The ship crew need to keep firing cannons, sniping, and patching up holes, and the raiders need to be ready for combat.
Cover image for YouTube videoHow To Get Started in Sea of Thieves

The first season has arrived! Learn about all Season 1 Battle Pass rewards and everything else added in the Sea of Thieves patch notes. New to the game? Learn what to do in Sea of Thieves and take take part in the Maiden Voyage tutorial, which teaches you the essentials of sailing and ship battles. It's also useful for beginners to know how to survive fights with skeletons and the kraken. Elsewhere we have advice on how to get easy gold and doubloons, complete skeleton forts and The Shroudbreaker, take part in fishing in Sea of Thieves and Sea of Thieves island maps.

How to defeat Skeleton Forts and get a Skeleton Stronghold Key

Once you have finished preparing, here's how to get complete the Skeleton Fort encounter and come away with a Skeleton Stronghold Key:

  • Keep the ship afloat at all times - We know this is basically a duplicate step but it is really important that you keep the ship afloat, because it's the place where pirates respawn, and as a raider you're going to be doing a lot of it. As long as the ship stands, you can have a steady stream of pirates charging onto land to keep the assault alive. As the assault progresses you can probably just keep one person back to do defend the ship, mind.
  • Defeat the waves of skeletons - The actual assault comes in the forms of several waves of enemies. Ideally, you want the ship to have line of sight to the battle so cannons can be used for some crucial support. On land, you need to deal with five types of enemy.
    • Basic Skeletons - essentially the same as any others you'll find around the world, these appear en masse.
    • Metal Skeletons - made out of solid treasure themselves, these take enormous amounts of damage but are heavily slowed by water. Throw buckets of water over them or better yet lead them to clustering up in a pool of water then detonate an explosive gunpowder barrel on them to take them down fast!
    • Seaweed Skeletons - think of these as the fast type of zombie, bet specifically when in water. They're erratic and rapid, and best defeated by kiting them to the beach for some cannon fire from the ship (although keeping them out of the water helps).
    • Black-boned Skeletons - these can be tricky, as they're only vulnerable in the light. Have one of your team shine a lantern at all times, or drag the battle out until daybreak if you want to defeat them!
    • Stronghold Captain - a much tougher version of the regular Skeleton Captains you'll find around the world, these are identified by the red name above them, but being just one enemy you can easily focus your fire - both from the ship and your crew - to gradually take them down.
  • Grab the Stronghold Key - On the Stronghold Captain's remains will be the Stronghold Key. Pick it up and head to the main tower's central keep.
  • Open the vault and make off with the loot! - When you find a glowing door, open it with the key to reveal a mound of highly valuable treasure (some items sell for about 3,000 coin a pop, for instance). It'll take several trips to take it back to the ship, and you may get attacked by skeletons or, worse yet, other crews that joined in the battle along the way, so we recommend some of you stick to guard duty and some do the carrying. Be sure to keep an eye out for other crews, keep your lanterns off if travelling at night, and book it to the nearest Outpost island to sell your stuff before you're looted by some crafty foe.

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Chris Tapsell

Deputy Editor

Chris Tapsell is Eurogamer's Deputy Editor and most decorated Football Manager. He used to write guides, and will send you links to his favourite spreadsheets if you ask him about League of Legends or competitive Pokémon.