Biomes

Biomes refer to the different types of areas that a Terraria world can contain. Biomes can each contain their own characteristic terrain blocks, collectible items, backdrops, background walls, enemies, critters, theme music, Angler Quest fish, and other traits.

The most common biomes are Forests, located on the surface. Going farther left or right will eventually lead to The Corruption/The Crimson, Deserts, Snow, Jungle, the Dungeon, and at the far right and left of the world, the two Oceans.

Space spans the entire width of the world above the surface. Below the surface, there are several underground biomes: They begin at the Cavern layer and include the Underground Mushroom biome, the Underground Jungle biome, the Underground Snow biome, and the Underground Desert. The very bottom of the world consists of The Underworld.

After the initial defeat of the Wall of Flesh in The Underworld, the world converts to Hardmode, and new areas of Corruption or Crimson will form, as well as a new biome, The Hallow, in addition to underground versions of those.

The Corruption, Crimson, and Hallow are all "contagious" biomes which spread to certain adjacent blocks. Prior to entering Hardmode, the Evil Biome will only slowly spread with its grass, but once Hardmode begins all three biomes will spread directly through most Soil blocks, Vines, and Thorny bushes.

Space

Space is a layer appearing at the top of the world: ~700 feet and above, for medium worlds. The sky is dark and stars are visible, even when the sun is still up, and low gravity affects players and enemies. Enemies will still spawn in Space, though to a lesser degree. Space has exclusive background and music, and its own distinctive enemies – Harpies from the start of the game and Wyverns and Arch Wyverns during Hardmode.

Surface/Underground

Biomes that appear above the Cavern layer operate as surface biomes, even though they can and do often extend underground, i.e. below 0ft. The actual "Underground" versions of biomes, such as the Underground Snow biome, with distinct underground characteristics, do not begin until Cavern layer depths.

Forest

Forests are the most common surface biome, and are where the player usually spawns upon starting a new world. Green grass grows across the dirt, which can spawn Mushrooms, Dayblooms, and Trees. Forests appear whenever no other biome is valid.

Snow

Snow biomes are winter-themed biomes predominately made of Snow and Ice Blocks. Snow falls constantly, though this is only an aesthetic effect. The Snow biome is always located opposite to the Jungle and thus on the same side of the map as the Dungeon. A minimum of 300 Snow or Ice Blocks are required for an area to count as a Snow biome.

Desert

Deserts are large expanses of Sand that require at least 1000 Sand or other Desert-themed blocks. They are common between Forests.

Corruption and Crimson

A world will always generate with an Evil Biome – either Crimson or Corruption, but never both. Each are hazardous biomes that offer access to important loot, crafting materials, and bosses. On the  PC,  Console,  Mobile,  tModLoader, and  tModLoader Legacy, the player is able to choose which biome their world is generated with, provided they have defeated the Wall of Flesh on a separate world, but otherwise it is a 50/50 chance of which one is randomly selected during world generation.

• The Corruption follows a spooky theme and features vertical chasms, Shadow Orbs, and Demon Altars.
• The Crimson follows a gory theme and features angled passages, Crimson Hearts, and Crimson Altars.

Jungle

The Jungle is a difficult surface biome composed of Jungle Grass, Vines, Mud and Mahogany Trees. The sky appears a vibrant green color. Mahogany Trees respawn automatically without the need to plant Acorns. The Jungle will always be located on the opposite side of the map from the Snow biome and Dungeon.

Dungeon

The Dungeon is a difficult labyrinth leading from the Surface down to near-Underworld depths. The Old Man stands at the entrance, and using him to defeat Skeletron is required to gain access to the inside. Heading below 0ft in the Dungeon without defeating Skeletron spawns one or more Dungeon Guardians, which have enormous defenses and are capable of one-hitting most players. The loot found in the Dungeon is rare, valuable, and some cannot be found elsewhere. The Dungeon is always located opposite to the Jungle and thus on the same side of the map as the Snow biome.

Ocean

Oceans consist of a deep body of water, where dangerous swimming enemies are found, and Water Chests contain ocean-themed loot. They are always located on both horizontal edges of the world.

Mushroom

The surface version of the Mushroom biome does not occur naturally, but can only be cultivated by players, using Mushroom Grass Seeds or an imported Clentaminator with Dark Blue Solution on surface-level mud. It will always appear darker than night, regardless of the time.

Cavern

The Cavern layer marks the beginning of distinct underground biome variants, with separate characteristics from their surface versions.

Underground Desert

The Underground Desert is a difficult biome located beneath the surface Desert. The biome is always sphere-shaped and contains various types of Antlions as well as ancient-Egyptian-themed enemies in Hardmode.

Underground Jungle

The Underground Jungle is a difficult biome located beneath the surface Jungle. Its dense catacomb of compartments contain several hazards and dense vegetation, as well as important loot and crafting materials. In Hardmode, valuable Chlorophyte Ore can be mined here. Three bosses can be fought in this biome: An Underground Jungle always contains several Bee Hives, where the Queen Bee boss is usually summoned. After the Mechanical Bosses have been defeated, Plantera's Bulbs spawn, allowing the player to summon Plantera, an important boss. The Jungle Temple is also located within the Underground Jungle, where the Golem boss can be summoned after Plantera is defeated.

Underground Mushroom

The Underground Mushroom biome features Glowing Mushrooms on top of Mud, and if there is enough height in the cavern, Giant Glowing Mushrooms can grow as well. It has a unique background and is the only place where Truffle Worms can be obtained.

Underground Snow

The Underground Snow is the Cavern layer's, more dangerous portion of the Snow biome and is located beneath the surface part. Many ledges and bodies of water will have a layer of Thin Ice over them, and while these can support the player's weight they can break when landing on them with high enough speed. This can be avoided with Ice Skates or Frostspark Boots. Ice Chests contain ice-themed equipment.

Underworld

The Underworld is a difficult biome located along the entire bottom of the world. Lava pools cover much of its terrain and dangerous enemies spawn frequently. Hellstone can be mined here, Ruined Houses offer valuable loot (some within their Shadow Chests), and unique furniture, and the Wall of Flesh boss can be summoned here in order to activate Hardmode. In Hardmode, the Tortured Soul spawns in the Underworld, which can be converted to the Tax Collector NPC using Purification Powder.

Hardmode

Hardmode biomes spawn or convert as a result of the game transitioning to Hardmode.

The Hallow

The Hallow can be considered the counterpart to the Evil Biome. It is automatically created once the player activates Hardmode by defeating the Wall of Flesh. The Hallow has pastel-colored imagery but is nevertheless highly difficult.

Underground Hallow

The Underground Hallow is located beneath the surface Hallow, starting at the Cavern layer. It has a different soundtrack from the surface Hallow, and contains even more difficult enemies as well as valuable items, like Souls of Light and Crystal Shards.

Underground Corruption

The Underground Corruption is created in the Cavern layer upon defeating the Wall of Flesh. It is not necessarily located beneath pre-Hardmode surface Corruption biomes. While it shares the theme with the surface Corruption, it has different enemies and a different soundtrack (a mix of the regular Underground and Corruption soundtrack). It is the only place to obtain Cursed Flames and Souls of Night, which are occasionally dropped by all enemies.

Underground Crimson

File:BiomeBannerUnderground Crimson.png

The Underground Crimson is the alternative to the Underground Corruption, which functions and is spawned in mostly the same way. The Underground Crimson, like the Corruption variant, will have enemies occasionally drop Souls of Night. It is the only place where enemies drop Ichor.

Corrupted/Crimson Deserts & Hallowed Deserts

When the world enters Hardmode, several Deserts of the world will become either corrupted, crimsoned, or hallowed. These have their own backgrounds, and spawn unique versions of the Mummy with unique drops. Sand is replaced by Ebonsand, Crimsand, or Pearlsand. It is possible for a pre-Hardmode world to be generated with a Corrupt or Crimson Desert.

Mini-Biomes

Biomes in this category tend to be small in number and size. They have unique characteristics and monster spawns.

Bee Hive

The Bee Hive is located in the Underground Jungle. Bee Hives are made from Hive blocks and contain honey and often a Larva. Destroying the Larva summons the Queen Bee boss. Breaking a Hive block may spawn a bee and/or some honey. There can rarely be two or three Bee Hives next to each other.

Granite Cave

The Granite Cave is a cave area made completely of Granite Blocks, usually fairly spacious with interspersed ledges and platforms. Granite Caves contain granite-themed enemies such as Granite Elementals and Granite Golems.

Jungle Temple

The Jungle Temple is a large, nearly impenetrable structure that spawns deep in the Underground Jungle. It is filled with powerful enemies and is only accessible after defeating Plantera, using the Temple Key she drops to open the door. In the largest chamber, there is a Lihzahrd Altar to spawn Golem.

Marble Cave

The Marble Cave is a cave area that is horizontal in shape and made completely out of Marble Blocks. Marble Caves contain ancient-Greek-themed enemies such as Hoplites and Medusas.

Meteorite

Whenever a Shadow Orb or a Crimson Heart is destroyed, there is a chance that within the next day the game will spawn a Meteorite and display the message "A meteorite has landed!". The meteor will crash into land and turn a large portion of the surrounding tiles into Meteorite. Meteorite will defect the player with the Burning debuff if they do not have an accessory that nullifies fire's effects, and/or an Obsidian Skin Potion. Mining Meteorite requires 50% pickaxe power, i.e. a Tungsten Pickaxe, Gold Pickaxe, or better is mandatory. Meteor Heads ( and, in Hardmode, Lava Bats) override all native enemies of the biome the meteor crashed into.

Spider Nest

A Spider Nest is characterized by the black background wall and the numerous webs filling the area. This biome will spawn Wall Creepers in Pre-Hardmode and Black Recluses during Hardmode. The Cobwebs rapidly grow back, which is a unique feature of the biome. Spider Nests are the only location where Web Covered Chests and all unique treasures discovered therein can be discovered. The Stylist NPC is found in this biome.

Micro-Biomes

Campsite

The Campsite is found in the Underground and Cavern layers usually containing a Campfire, Silver Coin Pile, and a background object of skeletal remains. The campsite is 12–20 blocks wide, and not quite as tall.

Gemstone Cave

A Gemstone Cave is filled with concentrated gem deposits of one or more varieties and features a unique background (a gemstone wall) that is speckled with gems of the same color found in the Gemstone Cave.

Moss Chamber

A micro-biome found in the Underground and Cavern layers that contains one color of Moss with a matching back wall.

Thin Ice Patch

A micro-biome found in the Underground Snow biome that is made entirely of Thin Ice and an occasional ore vein.

Treasure Rooms

Treasure rooms are spawned upon world creation and appear as if they were man-made structures. They generally contain loot and furniture.

Enchanted Sword Shrine

File:Enchanted Sword Shrine.png

The Enchanted Sword Shrine houses an Enchanted Sword, an Arkhalis, or a fake sword. Every shrine will contain one breakable background sword sprite, which has a 2/3 chance of being a fake sword and a 1/3 chance of being a real sword, which has a 1/10 chance of dropping the Arkhalis, instead of the Enchanted Sword, when destroyed.

Floating Islands

Floating Islands are independent masses of land in the sky. They contain a Skyware Chest with valuable loot.

Heart Shrine

Exclusive to the  Windows Phone version, Heart Shrines are heart-shaped caves sometimes found in Snow biomes. They hold two Crystal Hearts and a chest that may contain heart-themed items.

Jungle Shrine

Jungle Shrines are small brick buildings and typically contain only a single chest and a light source. They are found in the Underground Jungle and several can appear in one biome.

Jungle Sanctum

A Jungle Sanctum is a  Windows Phone-exclusive structure that occasionally appears in Jungles. Jungle Sanctums are a larger version of Jungle Shrines and contain Coin Stashes, along with an Ivy Chest that contains several jungle-themed items. There is also an Easter egg inside, a painting titled “Waldo” from a popular children’s book.

Living Tree

Living Trees are huge, thick trees consisting of foreground blocks (as opposed to regular background trees). Cutting the tree yields regular Wood. Some Living Trees can be hollow and lead deep underground. There may be rooms containing Living Wood Chests with related loot inside, as well as Living Wood furniture. It is not guaranteed that one will spawn in every world.

Pyramid

Pyramids are rarely generated in the Desert upon world creation. They are made of Sandstone Bricks and contain a narrow passage. The treasure room is filled with coins, vases and a Gold Chest that can contain unique loot. There is also a passage to a cave at the bottom. On Mobile, it can contain a second room separate from the passage blocked off by more Sandstone Bricks, containing similar loot to the first room.

Ruined House

Ruined Houses are generated upon world creation in The Underworld in the middle 50% of the Underworld. They are towers with multiple levels, constructed with missing parts for a "ruined" look, from Obsidian Brick or Hellstone Brick. They are sometimes partially submerged in lava and often contain deposits of Hellstone just outside their walls.

Underground Cabin

Underground Cabins are found in the Cavern layer. They are typically wooden buildings full of dusty, broken furniture as well as chests, vases, and occasionally usable furniture and decorations. As of 1.3.0.1, Underground Cabins spawn with blocks representing their biome.

Hybrid Biomes

While many of the basic biomes appear at world generation or triggered by events, it is possible for hybridized biomes to be synthesized by player action or, in Hardmode, by world mechanics.

Hybrid Biomes

Hybrid biomes are those created by the requirements being met for multiple biomes in a certain area. The simplest examples are Hallowed, Crimson, or Corrupt Deserts; however, not only Deserts can be hybridized. Floating Islands can be Corrupted/Crimsoned or Hallowed upon entry of Hardmode, and such high-layered biomes are even required by some Angler quests. Player action can similarly introduce Corruption, Crimson, Hallow, Desert, Jungle, Mushroom, Meteorite, or Snow biomes to any location from Underworld to Sky and likely even Space. This can lead to, for example in an Underworld Crimson, Underworld and Crimson enemies both spawning in the applicable areas.

Biome Existence Requirements

The area used for counting required blocks for the existence of biomes at a location appears to be 50 tiles to each side and approximately 42 below and 44 above, from the location of the player. Note that the "Compatible Biomes" column lists the biomes which can co-exist in the same general location, and has nothing to do with spreading mechanics.

Name	Block Requirements	Location	Compatible Biomes
Forest	n/a	Above the Underworld	Sky, Surface, Underground, Cavern, Ocean
Corruption	At least 200 Corrupt grass, Ebonstone Blocks, Purple Ice Blocks, Corrupt Thorny Bushes, or Vile Mushrooms	Any	Not Forest, Meteorite, or Hallow
Crimson	At least 200 (155 on  MobileVerify) Crimson grass, Crimstone Blocks, Red Ice Blocks, Crimson Thorny Bushes, Crimson vines, or Vicious Mushrooms	Any	Not Forest, Meteorite, or Hallow
Mushroom	At least 100 Mushroom grass or Glowing Mushrooms	Any	Not Forest or Meteorite
Jungle	At least 80 Jungle grass, Lihzahrd Bricks, Jungle Thorny Bushes, or Jungle vines	Any	Not Forest or Meteorite
Hallow	At least 100 Hallowed grass, Pearlstone Blocks, Pink Ice Blocks, or Hallowed vines	Any	Not Forest, Meteorite, Corruption, or Crimson
Desert	At least 1,000 Sand Blocks	Any	Not Forest or Meteorite
Corrupt Desert	At least 1,000 Ebonsand Blocks	Any	Not Forest, Meteorite, or Hallow
Crimson Desert	At least 1,000 Crimsand Blocks	Any	Not Forest, Meteorite, or Hallow
Hallow Desert	At least 1,000 Pearlsand Blocks	Any	Not Forest, Meteorite, Corruption, or Crimson
Ocean	At least 1,000 block spaces of Water	Outer lateral edges of the world, above Cavern layer	Not Meteorite, Corrupt Desert, Crimson Desert, or Hallowed Desert
Snow	At least 300 Snow Blocks, Ice Blocks, and possibly other Snow Biome blocks	Any	Not Meteorite or Desert
Meteorite	At least 50 Meteorite	Any	None
Dungeon	At least 250 Dungeon Bricks and a naturally-placed Wall other than Dirt Wall	Below -4 feet	None

Notes

• For Hallowed and Crimson/Corruption biome detection: There is a Hallowed value, a Crimson value, and a Corruption value. Each Hallowed block adds 1 to the Hallowed value and subtracts 1 from both the Crimson and Corruption values. Each Crimson block adds 1 to the Crimson value and subtracts 1 from the Hallowed value. Each Corruption block adds 1 to the Corruption value and subtracts 1 from the Hallowed value. This can be proven by placing 100 Hallowed blocks in an otherwise completely neutral area, observing that the area will change to Hallowed on placement of the 100th block, then that it will return to neutral on placement of a Crimson or Corruption block, then back to Hallowed on placement of an additional Hallowed block, ad infinitum.
• For Snow biome detection: While the area functionally changes to a Snow biome at 300 related blocks, the background of a Snow biome will not appear until 301 Snow biome blocks are present.
• For Dungeon biome detection: The game checks the number of Dungeon blocks (≥250), and checks only the single background wall the player is standing in front of. This wall must be naturally placed, from the original world creation.
• Inactive blocks (actuated blocks) will count towards the formation of a biome.