The Sunken Sea inCore Keeperis a massive underground ocean full of giant crabs and tentacles that fling muck. It’s guarded by an equally massive titan known as Omoroth, but that isn’t the only creature lurking beneath the glowing depths.

While it isn’t as hostile as Omoroth and holds no bearing toward The Core’s health, the Atlantean Worm is still a danger to any who brave the Sunken Sea. It won’t hesitate to hunt you down if you successfully manage to bring it to the surface, and defeating it brings you a trove of rewards – if you don’t get consumed.

Player character using a Boat Workbench to craft a Speeder boat in Core Keeper.

What To Bring To The Atlantean Worm’s Fight

The Atlantean isentirely located in the open waterof the Sunken Sea, aboat is pretty much requiredfor this fight, regardless of your class.

Boats arecrafted at a Boat Workbench, and the basic one can do the job, but you’ll want to go ahead andmake the Speeder Boat, as it’s got more thandouble the speed of its predecessor, allowing you toevade attacks betterand keep up with the boss.

Player character standing next to a Crystal Shard Club drop from an enemy in Core Keeper.

How To Obtain

Coral Wood Plank x200

Refine Coral Wood in aTable Sawthat’s powered by electricity. Coral Wood can be obtained by breaking Coral Wood Roots in any location in the Sunken Sea.

Octarine Bar x120

Smelt Octarine Ore in a Smelter Kiln. Octarine Ore can be mined from ore blocks, Octarine Ore Boulders with astationary drill, fished up from the water, or dropped by any enemy native to the Sunken Sea.

Gold Bar x30

Smelt Gold Ore in a Smelter Kiln. Gold Ore can rarely be found in any biome except for in The Underground, Gold Ore Boulders with a stationary drill, fished up in any water in any biome except for The Underground, or dropped by early and mid-game bosses likeGhorm the Devourer,Azeos the Sky Titan, andIvy the Poisonous Mass.

Mechanical Part x30

Obtain from opening Treasure Chests, breaking any type of breakable, opening Locked Chests, defeating Caveling enemies of any type, from early and mid-game boss reward chests, or purchased from the Cloaked Merchant after The Core has been activated.

Besidesone of the two boat types, you’ll also want adecent supply of good food dishes, preferably onesmade with mid-to-late-game cropslike the Pinegrapple,Sunrice, Lunacorn, andBloat Oatfor the besthealth recovery over timeand their buffs.

Player character crafting a Solarite Crossbow at a Solarite Anvil in Core Keeper.

You cantake the Guardian Potion to get a 12 percent reduction in damage takenfrom the Atlantean Worm and other bosses.

Potions are also key, and thebest one available for healingwill be theGreater Healing Potion, which is crafted withthree Poison Slimes and five Heartberries, and you canbring buff potionsas well to help your damage or defense.

Player character with the whole Arcane Monk set equipped showing the set bonus in Core Keeper.

Recommendations For Melee Characters

Similar to the fight against Ra-Akar, you’ll wantat least Octarine Armorfor this fight, butGalaxite or even Solarite will be betterfor raw defense, or if you want thebest of both worlds as far as damage and defense, you cantake some time to obtain the Godsent King Set.

Even if it’s not your primary damage type, it’sworth it to still have some kind of ranged weapon as a backup, such as the Galaxite Chakram or Octarine Bow.

Player character looking at the stats of an un-upgraded Tome of the Dead in Core Keeper.

Meleeweapons with a longer reach, such as theTentacle Whip or Anchor Axe, or ones that have aspecial skill with range, likethe Rune SongorCrystal Shard Club, will be thebest option for getting to the weak spotson the Atlantean Worm, but making sure youdon’t get too close and risk contact damage.

Recommendations For Ranged Characters

If you’re doing Ranged Melee Damage, theTassel Set from the Desert of Beginningsis still perfectly viable, but if you want some armor, you can alsoupgrade to the Cosmos Armor, as it provides ageneral damage buffof up to 34.5 percent, and theGodsent King Set worksas well.

TheNinja Set is also great for frequent critical hits, even if it doesn’t provide a Ranged Physical Damage buff, but it can be difficult to farm due to it only coming from fishing in Shimmering Frontier water or killing Nilipedes at low rates.

Player character buying the Bait Pillar from the Brave Merchant in Core Keeper.

For weapons, you’ll havequite a few things availablefor you: the Octarine Bow, theGalaxite Chakram, a fantastic ranged weapon thatprocs the Titan Souls' skills frequently,the Phantom Sparkif you don’t mind the exploration needed, or theSolarite Bow.

Recommendations For Magic Characters

For anyone using Magic Damage, theScholar Set still works, but you’re able to alsoupgrade to the Arcane Monk Setif you’ve started fighting the enemies in andexploring the Shimmering Frontier, and both theCosmos and Godsent King’s general damage buffcan help you out as well, while giving youplenty of armor.

If you’rewilling to brave the Passage and collect some Pandorium and Cytoplasm, and have found a Rift Statue, you can also use the Chaos Staff, ​​​​​​which decimates the boss.

Player character sailing on a Speed Boat and floating next to a placed Bait Pillar in Core Keeper.

As for weapons, theFireball Staff and Scholar Staffare still useful, especially if youupgrade them at an Upgrade Workbench, but you can also use theZealot’s Scimitarfor some close-range magic damage, or theSun Callerif you’vegotten it from Azeos the Sky Titan.

Recommendations For Summoner Characters

For those using Summons, theGrim set is still the best overallfor you, as it’s got thebest bonuses for Minionsas far as damage and Minion Count go, and provides you with thelargest amount of Mana Barrier.

If you want todo more damage on your ownand don’t mind having fewer Minions, you could alsouse the Arcane Monk setif you’regoing for Magic Damage, or, like with the other classes, use theGodsent King or Cosmos setif you prefer having Armor.

Player character fighting the Atlantean Worm while their summons attack it in Core Keeper.

Summons will still follow you if you’re on open water and will simply float above the water, somelee-based Summons will still work even if you’re on a boat.

For your actual summons,both melee and ranged types will work, but if you’reusing a melee-typelike theTome of the Deador Tome of Ashes, you’ll need tokeep closer to the Atlantean Wormduring the fight so they canbetter target the weak pointsand keep up with it.

How To Find And Summon The Atlantean Worm

The Atlantean Worm is aroaming bosslike Ghorm the Devourer, and follows aset oval path around the Sunken Sea, but with a much larger range than Ghorm.

You’ll want touse the Atlantean Worm Scannerto cause it to appear on the map, as this will let youtrack its path constantlyand make itmuch easier to locate.

Ancient Gemstone x15

Mining Ancient Ore nodes in any biome, breaking any type of breakable, opening any type of chest, killing Caveling enemies in biomes such as the Forgotten Ruins or Sunken Sea, or defeating Core Sentries.

Mechanical Part x15

Breaking any type of breakable, opening any type of chest, killing certain early or mid-game bosses, killing Caveling enemies in biomes such as the Forgotten Ruins or Sunken Sea, defeating Core Sentries, or defeating Orbital Turrets.

Solarite Bar x50

Smelt Solarite Ore in a Fury Forge. Solarite Ore can be obtained by mining ore nodes, using a stationary Drill on a Solarite Ore Boulder, killing Mimites, or mining the shell of Crystal Snails in the Shimmering Frontier biome.

Whether you use the Scanner to find it or not, you’ll alsoneed a special summoning itemto make it surface: theBait Pillar. This item can bebought from the Brave Merchant for 2,895 Ancient Coins, and they sell five of them at a time.

Tounlock the Brave Merchant, you’ll need to find an Alien Tech Lab scene in the Shimmering Frontier with a Challenge Arena, complete the arena, and obtain the Nuclear Battery Idolas a reward.

Once you’ve bought the Bait Pillar, teleport to the Sunken Sea and use your boat tosail out onto the open water, and thenwatch the Atlantean Worm’s pathon the map or begin sailing around until youfind it and can follow it.

When you catch up with it,place the Bait Pillar downon the water withinat least 50 tiles of the Atlantean Worm, and this will trigger its boss fight,making it surfaceand its health bar appear.

Be careful not to get trapped beneath the Atlantean Worm’s massive body as it surfaces, as it’spossible to get surrounded by its body or get caught beneath it, and end up instantly dying due to the stacking contact damage.

How To Beat The Atlantean Worm

The Atlantean Wormprimarily attacksby trying tobite you or ram its spikes into you, while occasionally using along-range magic attackwhere it summons aball of energy that splits into smaller ballsas they travel.

Thereal challengein this fight comes in that you canonly damage it in certain weak pointsthat appear along its body asdarker blue chunks of skin​​​​​​in between its segments, and upondestroying these weak points, the Atlantean Worm willspawn another, smaller worm.

Each of these worms will do thesame attacks as the original, have a similarweak point with a health bar, and will continue tospawn additional worms as you kill them.

Weapons with a piercing skill, such as theCrystal Spike Club or Solarite Bow, are great for hitting multiple segments at one time.

All the Atlantean Worms need to be killed to complete the boss fight, and there tend to bearound ten worms in totalthroughout the fight, but once thatlimit is reached, killing the smallerworms won’t spawn anymore.

Try tofocus on one segment at a time, as this allows you tobetter evade their attacks, and you can try andkeep the number of worms in the fight lowby only killing one at a time. Make sure toavoid getting trapped between multiple wormsas well, especially sincedodge skillsfrom Off-handswon’t work while you’re in a boat.

Circle along the Atlantean Wormsas they move, keepingtowards their backendso you havetime to see what direction they’ll goin next andavoid as much contact damageas possible.

If youhave the HP to do so, you can also go in close along their side and get a ton of hits in before sailing away, but this strategy works better with the Speeder Boat.

Once you beat the Atlantean Worms, theAtlantean Worm Chestwill spawn on the waterfor you to take from, or it may break, and theitems drop on the waterif thechest was hit by a leftover attack.

As a reward, you’reguaranteed to receive the Atlantean Worm Heart, one of thepermanent Health-boosting items, and have achance to get other dropssuch as theAtlantean Worm Sword,Atlantean Worm set, theSun Caller staff, and minor items like Sunken Sea fish.