Sulphurous Sea

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The Sulphurous Sea, also known as the Sulphur Sea, is a biome added by the Calamity Mod which spawns upon world creation. It replaces the Ocean on the Dungeon side, and is located on top of the Abyss. Its water is turquoise colored, and it contains a hole leading to the Abyss.

It is primarily composed of Sulphurous Sand that makes up multiple islands that generate at sea level, where Acidwood Trees will grow when not covered by water. A series of caves composed of Sulphurous Sandstone and Hardened Sulphurous Sandstone will generate between the surface of the Beach and the Abyss, where Rusty Chests can be found. Coral, Seashells and Starfish also grow faster in this biome, and many new decorative objects such as Corroded Fossils and Pillars will generate in the Sulphuric Caves.

Dangerous Sulphuric Bubbles can generate above any Sulphuric Sand or Sandstone when they are covered by water. These bubbles can't hurt the player until they have reached their maximum size. They deal 20 damage and inflict Acid Venom for 2 seconds. The water is also hazardous, inflicting Sulphuric Poisoning that grows more damaging the longer the player stays in it. Steam Geysers also generate on the Beach, and will fire steam at the player if they walk over them.

Acid Rain can start in this biome at any time after the Eye of Cthulhu has been defeated. Acid Rain will cause numerous new enemies to spawn throughout the game at multiple points of progression, many of which have new drops.

The Aquatic Scourge boss can spawn here naturally (but very rarely) or can be summoned here by using Seafood, and The Old Duke can be summoned here by using Bloodworms as bait when fishing.


Sulphurous Sea
CharactersUnique TreasuresUnique DropsMusic
Aquatic UrchinAquatic Urchin
Catfish (enemy)Catfish

If Aquatic Scourge has been defeated:

Anthozoan CrabAnthozoan Crab
Baby Flak CrabBaby Flak Crab(Critter)
Belching CoralBelching Coral

After the Moon Lord has been defeated:



Aquatic ScourgeAquatic Scourge
The Old DukeThe Old Duke
From Rusty Chests:
Broken Water FilterBroken Water Filter
Effigy of DecayEffigy of Decay
Rusty Beacon PrototypeRusty Beacon Prototype
Rusty MedallionRusty Medallion

From Pots:

Sulphuric TreasureSulphuric Treasure

From Aquatic Urchin:

Urchin StingerUrchin Stinger

From Flounder:

Anechoic CoatingAnechoic Coating

From Trasher:

Trash Can (pet)Trash Can (pet)

From Catfish and Trasher:

Diving HelmetDiving Helmet

From Gnasher in Hardmode:

Turtle ShellTurtle Shell

From Trasher in Hardmode:


From Baby Flak Crabs caught with a Bug Net:

Geyser ShellGeyser Shell

From Anthozoan Crabs and Belching Corals:

Corroded FossilCorroded Fossil

From Belching Corals:

Belching SaxophoneBelching Saxophone

From terrain:

Sulphurous SandSulphurous Sand
Sulphurous SandstoneSulphurous Sandstone
Hardened Sulphurous SandstoneHardened Sulphurous Sandstone
Rusty ChestRusty Chest

From Fishing:

Abyssal CrateAbyssal Crate
Abyssal AmuletAbyssal Amulet
Alluring BaitAlluring Bait
Planty MushPlanty Mush
Pink Jellyfish (bait)Pink Jellyfish (bait)
Red SnapperRed Snapper
Music Box (Sulphurous Sea)Music Box (Sulphurous Sea)


When fishing in the Sulphurous Sea the player can catch Abyss related items, these depend on the player's fishing power, and are as follows:

  • Abyssal Crate - Can be caught with any fishing power.
  • Planty Mush - Can only be caught with 0 to 80 fishing power.
    • Planty Mush's coded requirement is actually 40 to 80. However, as this item replaces Junk catches in the Abyss, it is technically 0 to 80.
  • Alluring Bait - Can only be caught with 40 to 159 fishing power.
  • Abyssal Amulet - Can only be caught with 110 to 239 fishing power.


Map Background Sulphurous Sea.png
Bestiary and Map Background.
  • The Sulphurskin Potion and Sulphurous armor will reduce the damage taken from the sulphuric water. The Effigy of Decay will grant the player complete immunity to the sulphuric water.
  • Player-created Sulphurous Sea biomes are possible by placing more than 300 blocks of Sulphurous Sand, Sulphurous Sandstone, or Hardened Sulphurous Sandstone in an area.
  • The Sulphurous Sea biome is defined by world position rather than the blocks present, meaning that a Dungeon-side Ocean initially generated without Calamity installed will still be considered as a Sulphurous Sea, and contain all of its enemies and effects. An artificial Sulphurous Sea can also be created by using Sulphurous Sand.
  • For an unknown reason, the Sulphurous Sea can generate within another biome, resulting in no entrance to the Abyss.
  • The Suphurous Sea can also generate entirely underwater, making the biome much more dangerous.
  • Sulphurous Vines grow underneath blocks below the sea's surface, and emit a bright green light.
  • Microbial Clusters can also be found in the Sulphurous Sea. They are passive NPCs that spawn at any point in the game, and move around in random directions. They are invisible, but emit particles which glow a bright green light.


  • This area is very dangerous for early game players, as it houses several fast high-damage enemies, like the Trasher, and the area's poisonous water will quickly drain an unprepared player's health.


  • The theme heard while in the Sulphurous Sea is wasteland, which was composed by the artist DM DOKURO.
    • If the Calamity Music add-on mod is disabled, the Desert's theme will play instead.
  • The turquoise coloration of the water is representative of real life volcanic sulfuric lakes.
  • The enemies found within the Sulphurous Sea are immune to almost all debuffs, possibly referencing their adaptation to the toxic environment.
  • Due to the urine-like coloration of the biome's water in previous versions of the mod, this biome has been known by the community as the "piss sea" or "piss ocean".