Before Skeletron falls, don't take the Dungeon below Surface depth: a Dungeon Guardian will come for you and can kill you in one hit. That same depth shift changes every cave: one tunnel can hold a chest, a trap or a fight you're not ready for. Learn each region's layer before you dig, and the underground stops being a gamble.
Region
Surface and edges
Forest
Start here for wood, stone and clay, and watch the outer sixths, where a rare King Slime can show up.
- World Layer
- Surface
- How to Find It
- The default surface terrain fills any spot no other biome claims. Grass, trees, ponds and open cave mouths mark it.
- Key Enemies
- Slimes, Demon Eyes and Zombies. Goblin Scouts and Goblin Archers turn up in the outer sixths, and a rare King Slime can spawn there too.
- Resources and Landmarks
- Wood, Clay and Stone for your first base, plus surface Chests.
- Hazards
- The outer sixths can surprise you, with Goblin Scouts, Goblin Archers and a rare King Slime.
- Hardmode Change
- Possessed Armor, Wandering Eyes and Wraiths join the night spawns in Hardmode, with Werewolves on full moons. The Hallow and evil can erase Forest grass, and Purification Powder restores it.
Desert
A hot, sandy stretch with Cactus and palms, where a sandstorm can turn a simple crossing into a fight.
- World Layer
- Surface
- How to Find It
- A wide sandy region on the same side of the world as the Jungle, opposite the Snow biome and Dungeon.
- Key Enemies
- Vultures and Antlions before Hardmode. Sandstorms bring special spawns once the wind passes 30 mph.
- Resources and Landmarks
- Cactus and Waterleaf grow here, and palm trees mark any Oasis inside the Desert.
- Hazards
- Sandstorms bring special spawns, so cross the open sand with a plan.
- Hardmode Change
- Corruption, Crimson and Hallow convert the sand. The converted Desert brings Mummies (Dark, Blood or Light) and Sand Sharks.
Oasis
Palms and a pool make a handy fishing stop, and the Oasis Crate is available before Hardmode.
- World Layer
- Surface
- How to Find It
- Look for palm trees around a large pool inside a Desert. You can also make one by placing enough water in the Desert.
- Key Enemies
- The Desert's own critters and enemies. The Oasis has no unique spawns.
- Resources and Landmarks
- Oasis fishing gives Oysters and the Oasis Crate before Hardmode, plus the Mirage Crate in Hardmode. Palm trees drop Palm Wood.
- Hazards
- Sandstorms and the Desert's spawns still apply around the pool.
- Hardmode Change
- A Hallowed Oasis can catch Hallowed fish as well as Oasis fish.
Snow
Gather Boreal Wood, watch for Blizzards, and keep an eye out for Deerclops at midnight.
- World Layer
- Surface
- How to Find It
- The snowy surface region on the same side of the world as the Dungeon, opposite the Jungle and Desert.
- Key Enemies
- Ice Slimes by day and Frozen Zombies at night. Hardmode brings Wolves and Ice Elementals at night, and rare Ice Golems in Blizzards.
- Resources and Landmarks
- Boreal Wood, which snow trees always drop when cut, and Shiverthorn that grows in the snow.
- Hazards
- Blizzards cut visibility during rain, and Deerclops can show up at midnight during one.
- Hardmode Change
- Corruption, Crimson and Hallow can convert Ice Blocks, but Snow Blocks resist them, so much of the surface Snow biome stays intact.
Jungle
The Jungle is a humid green stretch whose underground rewards are worth the trip, but Piranhas watch the pools.
- World Layer
- Surface and its Underground Jungle
- How to Find It
- The Surface Jungle lies on the Desert side of the world. Follow Mud and Jungle Grass down to find its Underground Jungle.
- Key Enemies
- Surface: Snatchers, Piranhas and Jungle Bats. Underground: Jungle Slimes, Spiked Jungle Slimes, Hornets and Man Eaters. Hardmode adds Derplings, Giant Flying Foxes, Moss Hornets, Jungle Creepers, Angry Trappers, Arapaimas, Giant Tortoises and rare Moths.
- Resources and Landmarks
- Mahogany trees, Vines and Jungle Grass. Underground Life Fruit starts after one mechanical boss; Plantera's Bulbs start after all three, and Chlorophyte grows there from Hardmode.
- Hazards
- Piranhas lurk in the pools, and thorny growth slows you down.
- Hardmode Change
- Corruption and Crimson can convert Jungle Grass, while Hallow cannot spread through Mud. Chlorophyte starts growing in the Underground Jungle when Hardmode begins.
Ocean
Both edges hold Water Chests, coral and fishing crates, but Sharks guard the seabed.
- World Layer
- Surface, both world edges
- How to Find It
- Travel to either far edge of the world, where the surface drops into a large body of water.
- Key Enemies
- Crabs, Pink Jellyfish and Sharks, with Squids and Sea Snails rarely showing up underwater. Orcas join in Hardmode.
- Resources and Landmarks
- Coral and seashells on the seabed, Palm Wood from beach palms, Water Chests and Ocean crates from fishing.
- Hazards
- Deep water and Sharks make a seabed search costly.
- Hardmode Change
- Orcas join the ocean, and its enemies can drop Pirate Maps.
Space
The sky holds Fallen Stars and Skyware Chests, but Harpies and Wyverns make the climb costly.
- World Layer
- Above the Surface
- How to Find It
- Climb above the Surface until the sky darkens and gravity feels lighter. Floating Islands rise into this layer.
- Key Enemies
- Harpies and Clumsy Balloon Slimes before Hardmode. Wyverns join in Hardmode, and Martian Probes appear after Golem falls.
- Resources and Landmarks
- Fallen Stars drop in the sky, and Floating Islands hold Skyware Chests. Space fishing needs a pure Space biome.
- Hazards
- Harpies attack from the air, and a missed jump from a Floating Island is a long way down.
- Hardmode Change
- Wyverns join the sky's enemies, and Martian Probes appear after Golem falls.
Region
Underground and Caverns
Underground
Early ore, Blinkroot and Underground Cabins make the layer worth a dig, but Dart Trap Slimes hide in the tunnels.
- World Layer
- Below the Surface, above the Caverns
- How to Find It
- Dig below the Surface until the Depth Meter reads Underground. Use the readout rather than a fixed depth.
- Key Enemies
- Giant Worms, Blue Slimes and Blue Jellyfish early on, with Pinky rare. Hardmode brings Diggers and Possessed Armor.
- Resources and Landmarks
- Ore veins, gems, Underground Cabins and Blinkroot.
- Hazards
- Dart Trap Slimes and hidden traps are common, so check the floor before you run.
- Hardmode Change
- Diggers largely replace Giant Worms, Toxic Sludge largely replaces regular slimes, and Green Jellyfish replace most Blue Jellyfish.
Caverns
Most deep mining happens here. Watch for lava pools and traps while you hunt cabins and ore.
- World Layer
- Cavern layer
- How to Find It
- Keep digging until the readout says Cavern. The Caverns are the broad stone layer above the Underworld.
- Key Enemies
- Cave Bats, Skeletons and rare Nymphs early on. Hardmode adds Armored Skeletons, Giant Bats, Rock Golems and Skeleton Archers.
- Resources and Landmarks
- Underground Cabins with valuable loot, plus gems and deep ore.
- Hazards
- Pools of lava in the lower Caverns, and traps such as Dart Traps and Geysers.
- Hardmode Change
- Underground Corruption, Crimson and Hallow reach this layer, and Hardmode adds its cave enemies.
Ice Biome
The Ice Biome is Snow's cave twin, with Frozen Chests and thin ice that breaks under a long fall.
- World Layer
- Cavern layer beneath Snow
- How to Find It
- Descend below the Snow biome. Ice blocks and the Ice Biome's own background and enemies mark the region.
- Key Enemies
- Ice Bats, Snow Flinxes, Undead Vikings and Slush Slimes before Hardmode. Armored Vikings, Ice Tortoises, Ice Elementals, Icy Mermen and Ice Mimics spawn in Hardmode.
- Resources and Landmarks
- Frozen Chests, which only generate here, and ice blocks for building.
- Hazards
- Thin Ice forms over water and breaks when you land on it after falling more than four tiles. Ice Skates and their upgrades stop the break.
- Hardmode Change
- Corruption, Crimson and Hallow can convert Ice Blocks into Purple, Red or Pink Ice. Their enemies join the Ice Biome pool, including Pigrons; Snow Blocks still resist conversion.
Underground Desert
Sandstone chambers hold fossils, Amber and chests, but Antlion Chargers make narrow tunnels a fight.
- World Layer
- Underground and Caverns beneath the Desert
- How to Find It
- Search below a Surface Desert for round or oval sand caverns with Sandstone and Hardened Sand walls.
- Key Enemies
- Antlion Chargers and Swarmers, Giant Antlions, Tomb Crawlers and Sand Slimes before Hardmode. Basilisks and Ghouls come in Hardmode.
- Resources and Landmarks
- Desert Fossils, Amber, Sandstone Chests and the Golfer, who is found here.
- Hazards
- Narrow chambers and Antlion Chargers make a crowded fight, so keep room behind you.
- Hardmode Change
- Corruption, Crimson and Hallow infect the sand and bring their own Ghouls, Lamias and Desert Spirits.
Underground Jungle
Life Fruit and Plantera Bulbs make the trip worthwhile, but thorns and water slow every tunnel.
- World Layer
- Underground and Caverns beneath the Jungle
- How to Find It
- Dig below the Jungle until Jungle Grass, Mud and the Underground Jungle background take over.
- Key Enemies
- Jungle Slimes, Spiked Jungle Slimes, Hornets, Man Eaters, Jungle Bats and Bees before Hardmode. Hardmode adds Moss Hornets, Jungle Creepers, Angry Trappers, Arapaimas, Giant Tortoises and rare Moths.
- Resources and Landmarks
- Jungle Spores, Stingers, Vines and Mahogany. Life Fruit starts after the first mechanical boss; Plantera's Bulbs appear after all three, and Chlorophyte grows here in Hardmode.
- Hazards
- Thorns and water slow movement, and Hornets and Man Eaters are the main threats.
- Hardmode Change
- Hardmode adds new underground enemies and lets Corruption or Crimson convert Jungle Grass. Chlorophyte starts growing in the Cavern layer; Hallow cannot spread through Mud.
Glowing Mushroom
Mushroom caves are the only source of Truffle Worms, and a surface patch can be built to house the Truffle.
- World Layer
- Underground and Caverns; player-built Surface
- How to Find It
- Natural mushroom biomes generate underground in the Caverns. Plant Mushroom Grass Seeds on Mud to make one above the Surface.
- Key Enemies
- Surface Mushroom Grass draws Spore Zombies, Anomura Fungus, Fungi Bulbs and Mushi Ladybugs. Underground, Spore Bats and Spore Skeletons spawn before Hardmode; Anomura Fungus, Fungi Bulbs, Mushi Ladybugs, Fungo Fish and Giant Fungi Bulbs join in Hardmode.
- Resources and Landmarks
- Glowing Mushrooms and Mushroom Grass Seeds grow here. Truffle Worms spawn only in underground Glowing Mushroom biomes during Hardmode.
- Hazards
- Darkness in the caves can hide enemies and traps.
- Hardmode Change
- Hardmode adds mushroom enemies to underground biomes. Mushroom Grass resists Corruption and Crimson, though the initial Hardmode stripe can still convert plain Stone inside the biome.
Glowing Moss
Wide patches of glowing moss light up the Caverns, and each world uses one gas-named variant.
- World Layer
- Cavern layer, away from spawn and the horizontal center
- How to Find It
- Look for wide Stone patches glowing with Krypton, Xenon, Argon or Neon Moss. They generate in the Caverns, usually above lava and away from the map center; all glowing-moss biomes in one world share the same variant.
- Key Enemies
- No unique enemies. Ordinary Cavern enemies can still show up.
- Resources and Landmarks
- Glowing moss blocks in the variant your world rolled, for building and decoration.
- Hazards
- Cavern darkness, traps and cave enemies still apply.
- Hardmode Change
- -
Granite Cave
The blue granite cave is easy to spot, and its Geodes and Granite Blocks are worth carrying home.
- World Layer
- Underground and Caverns
- How to Find It
- Look for a broad pocket of Granite Blocks with matching walls and ledges.
- Key Enemies
- Granite Elementals and Granite Golems, both pre-Hardmode Granite Cave enemies.
- Resources and Landmarks
- Granite Blocks, Granite furniture and Geodes. Each Granite enemy drops a Geode about one time in twenty.
- Hazards
- Granite Elementals are dangerous, so explore once your gear can handle them.
- Hardmode Change
- Hardmode adds no Granite-specific enemy. The surrounding Cavern still gets its Hardmode enemy spawns.
Marble Cave
Long marble caves hold Hoplites early, and Medusa's Stoned debuff makes Hardmode a different fight.
- World Layer
- Underground and Caverns
- How to Find It
- Look for long horizontal caverns of Marble Blocks, with platforms and ledges through them.
- Key Enemies
- Hoplites before Hardmode. Medusas join in Hardmode.
- Resources and Landmarks
- Marble Blocks and Marble furniture. Hoplites drop Gladius, Javelin and Gladiator armor, and Medusas drop Medusa Head and Pocket Mirror.
- Hazards
- Medusa's Stoned debuff can hit you from a distance, so break line of sight when she is near.
- Hardmode Change
- Medusas join the cave's enemies in Hardmode, and their Stoned debuff can reach from far away.
Spider Nest
Thick webs lead to the Webbed Stylist and rare treasure, but the spiders come from walls and ceilings.
- World Layer
- Underground and Caverns
- How to Find It
- Look for black background walls and thick webs. The cobwebs regrow inside the nest.
- Key Enemies
- Wall Creepers before Hardmode. Black Recluses join in Hardmode.
- Resources and Landmarks
- The Webbed Stylist can be found here, rare Web-Covered Chests show up, and the Web Slinger is one of the nest's treasures.
- Hazards
- Webs slow you down, and spiders attack from walls and ceilings.
- Hardmode Change
- Black Recluses join the Wall Creepers in Hardmode.
Region
Corruption, Crimson and Hallow
Corruption
Purple world evil with deep chasms, Shadow Orbs and Demonite Ore, and a spread that gets harder to stop in Hardmode.
- World Layer
- Surface, Underground and Caverns
- How to Find It
- Purple grass, Ebonstone and deep chasms mark it. A standard world gets either the Corruption or the Crimson, never both.
- Key Enemies
- Eater of Souls, Devourers and Corrupt Goldfish before Hardmode. Hardmode adds Corruptors, Corrupt Slimes, Slimers and World Feeders.
- Resources and Landmarks
- Demonite Ore from the Eater of Worlds and Shadow Orbs at the ends of chasms. World Feeders drop Cursed Flames, and eligible enemies in the Underground Corruption can drop Souls of Night.
- Hazards
- Chasms and fast enemies make a careless descent risky.
- Hardmode Change
- Hardmode's evil stripe runs diagonally from the Surface to the Underworld, creating Underground Corruption through the Caverns. The Corruption can then spread through more eligible blocks.
Crimson
The red world evil trades Corruption's chasms for vein-like caves, with Crimtane Ore and Ichor on the route.
- World Layer
- Surface, Underground and Caverns
- How to Find It
- Red grass, Crimstone and vein-like chasms mark it. A standard world gets either the Crimson or the Corruption.
- Key Enemies
- Blood Crawlers, Face Monsters and Crimeras before Hardmode. Hardmode adds Herplings, Crimslimes, Blood Feeders and Ichor Stickers.
- Resources and Landmarks
- Crimtane Ore from the Brain of Cthulhu and Crimson Hearts at the ends of chasms. Ichor drops from Ichor Stickers in the Underground Crimson, and eligible enemies there can drop Souls of Night.
- Hazards
- Chasms and aggressive cave enemies punish a blind descent.
- Hardmode Change
- Hardmode's evil stripe runs diagonally from the Surface to the Underworld, creating Underground Crimson through the Caverns. The Crimson can then spread through more eligible blocks.
Hallow
Storybook scenery and Crystal Shards, but the Underground Hallow is a dangerous Hardmode trip.
- World Layer
- Surface, Underground and Caverns
- How to Find It
- The Hallow appears as a diagonal band of pastel grass and crystal after the Wall of Flesh falls.
- Key Enemies
- Pixies, Unicorns and Gastropods on the surface. The Underground Hallow adds Chaos Elementals and Illuminant Slimes and Bats.
- Resources and Landmarks
- Crystal Shards grow on exposed Pearlstone, and Pixies drop Pixie Dust. Eligible enemies in the Underground Hallow can drop Souls of Light about one time in five.
- Hazards
- The Underground Hallow is one of Hardmode's dangerous biomes, so arrive geared up.
- Hardmode Change
- Hardmode creates a diagonal Hallow stripe from the Surface to the Underworld. The Hallow then spreads through eligible grass, stone, sand and ice.
Region
Special regions
Dungeon
Explore the entrance early, but save the deep halls for after Skeletron falls.
- World Layer
- Surface entrance, deep halls below
- How to Find It
- The brick castle entrance sits on the Snow side of the world, opposite the Jungle. Before Skeletron falls, stay above Surface depth inside it; crossing below that line summons a Dungeon Guardian.
- Key Enemies
- Angry Bones and Dark Casters before Hardmode. After Plantera, wall-dependent enemies include Armored Bones, Necromancers, Ragged Casters, Diabolists and Paladins.
- Resources and Landmarks
- Locked Gold Chests need Golden Keys. The Bound Mechanic can be freed by speaking to her, and Biome Chests become openable after Plantera with their matching keys.
- Hazards
- Traps and enemy groups fill the halls. Going below Surface depth before Skeletron summons a nearly invulnerable Dungeon Guardian that usually kills in one hit; killing it does not unlock the Dungeon.
- Hardmode Change
- After Plantera, new wall-dependent enemies spawn and the Dungeon Biome Chests can be opened with their keys.
Jungle Temple
Find the Temple early if you like, but its door and trapped halls are built for after Plantera falls.
- World Layer
- Deep in the Underground Jungle
- How to Find It
- Search deep in the Underground Jungle for the Lihzahrd Brick structure. Plantera drops the Temple Key that opens its locked door.
- Key Enemies
- Lihzahrds and Flying Snakes inside the Temple.
- Resources and Landmarks
- Lihzahrd Chests with Power Cells and Solar Tablets, and the Lihzahrd Altar that summons Golem for one Power Cell.
- Hazards
- Pressure plates trigger Flame Traps, Spear Traps, Spiky Ball Traps and Super Dart Traps. These are far more dangerous than Dungeon traps.
- Hardmode Change
- The Temple is always in the world, but Plantera's defeat is the gate that lets you enter it properly.
Graveyard
A Graveyard gives you Ecto Mist recipes and special shop stock, but it brings night enemies into daylight.
- World Layer
- Player-created, Surface and underground
- How to Find It
- Place Tombstones close together. Visual effects start at five, but seven are needed for the Graveyard's functional effects; each nearby Sunflower raises the threshold by one.
- Key Enemies
- Ravens, Ghosts, Maggot Zombies and Moss Zombies on the surface, day and night. Statues show up after Skeletron, and Hoppin' Jacks in Hardmode. Underground Graveyards spawn no enemies.
- Resources and Landmarks
- Ecto Mist unlocks special crafting recipes, and vendors carry Graveyard-only stock.
- Hazards
- Night enemies come out during the day, and Ecto Mist can hide Pressure Plates.
- Hardmode Change
- A Dryad housed in a Graveyard sells the seeds of the evil biome your world doesn't have.
Meteorite
The crater gives early Meteor gear, but touching the ore sets you on fire and Meteor Heads come through walls.
- World Layer
- Surface crater
- How to Find It
- After the world's first Eater of Worlds or Brain of Cthulhu defeat, meteorites can start falling. On PC, smashing Shadow Orbs or Crimson Hearts alone is not enough. Search the Surface for a crater.
- Key Enemies
- Meteor Heads, which only spawn in a Meteorite biome and fly through solid blocks.
- Resources and Landmarks
- Meteorite ore, which smelts into bars for early Meteor gear.
- Hazards
- Touching Meteorite blocks sets you on fire. Water and honey won't stop it, but an Obsidian Skull or Obsidian Skin Potion will protect you.
- Hardmode Change
- Meteorites can still fall in Hardmode, so the sky remains a source of ore.
The Aether
A Shimmer pool ringed by Gem Trees sits in the outer fifth of the Jungle side, and it transforms items and critters.
- World Layer
- Underground or Caverns, outer fifth on the Jungle side
- How to Find It
- Search the outer fifth of the world on the Jungle's side, in the Underground or Caverns. Only a single Aether can generate per world.
- Key Enemies
- Shimmer Slimes form from most slimes that enter the pool, and Faelings flutter above it. Most critters dropped into Shimmer become Faelings; gem critters turn into matching gems.
- Resources and Landmarks
- The Shimmer pool, Gem Trees and item transmutations. Before Moon Lord, the natural Aether is the world's only Shimmer source.
- Hazards
- Entering Shimmer makes you sink through solid blocks until you reach an opening, so check where the fall leads before stepping in.
- Hardmode Change
- -
Bee Hive
A Bee Hive can double as a Queen Bee arena, so check your position before you break the Larva.
- World Layer
- Underground Jungle
- How to Find It
- Hive Blocks in the Underground Jungle hide a Larva. Breaking Hive Blocks releases Bees.
- Key Enemies
- Bees released from the Hive.
- Resources and Landmarks
- Hive Blocks, Honey and Larvae.
- Hazards
- Breaking the Larva starts the Queen Bee fight, so check your position before you swing.
- Hardmode Change
- Moss Hornets join the Underground Jungle's enemies in Hardmode.
Town
A Town cuts ordinary spawns in Classic and keeps NPCs close, but Expert and Master still leave a small spawn chance.
- World Layer
- Player-created, any layer
- How to Find It
- Three or more friendly NPCs living close together form a Town. Town Pets count toward it.
- Key Enemies
- No unique enemies. Three nearby friendly NPCs, including Town Pets, form a Town. Outside the Underworld, Graveyards, world evil and Meteorite biomes, Classic blocks ordinary spawns; Expert and Master retain a 1-in-30 spawn chance per tick. Events and bosses bypass the rule.
- Resources and Landmarks
- Housed NPCs for shops and services.
- Hazards
- Events and bosses ignore the spawn reduction, so a Town won't keep out invasions.
- Hardmode Change
- The same difficulty-based Town spawn rules apply in Hardmode; biome, layer and events still affect them.
Region
Underworld
Underworld
Hellstone, Shadow Chests and the Wall of Flesh route, with lava leaving little room for mistakes.
- World Layer
- Bottom of the world
- How to Find It
- Keep digging through the Caverns until the readout hits the bottom layer. Lava fills much of the floor.
- Key Enemies
- Hellbats, Lava Slimes, Fire Imps, Demons, Voodoo Demons and Bone Serpents. Hardmode adds Mimics and Tortured Souls; Red Devils and Lava Bats arrive after a mechanical boss.
- Resources and Landmarks
- Hellstone, Ash Blocks, and Ruined Houses with Shadow Chests. Shadow Chests need a Shadow Key.
- Hazards
- Hellstone burns when touched, and lava is everywhere. A Guide Voodoo Doll dropped into lava summons the Wall of Flesh, and a Voodoo Demon killed over lava can do it by accident.
- Hardmode Change
- Mimics and Tortured Souls appear in Hardmode. After a mechanical boss falls, Red Devils and Lava Bats join the Underworld spawns.
Ash Forest
Ash Trees line both edges of the Underworld, a rare bit of cover in the lava layer.
- World Layer
- Outer sixths of the Underworld
- How to Find It
- Ash Trees grow from Ash Grass in the leftmost and rightmost sixths of the Underworld.
- Key Enemies
- No unique enemies. The ordinary Underworld roster appears here.
- Resources and Landmarks
- Ash Wood from the trees and Ash Blocks from the ground.
- Hazards
- Lava and fire hazards from the Underworld still apply.
- Hardmode Change
- The Underworld changes apply here too: Mimics and Tortured Souls appear in Hardmode, then Red Devils and Lava Bats after a mechanical boss.
Learn the layers before you dig
Space sits above the Surface, the Underground and Caverns run below it, and the Underworld is the bottom layer. A Depth Meter tells you which one you're in, and that matters more than any single biome name. In a standard world, the Snow biome and the Dungeon share one side of the map, while the Jungle and Desert share the other, and Oceans sit at both edges.
Pick a surface route with a reason
A Forest is the best place to gather Wood, Stone and Clay for your first base. The Desert trades that for Cactus, Waterleaf and an Oasis pool worth fishing. Snow gives you Boreal Wood, but its Blizzards can bring Deerclops at midnight. The Jungle is the route to its deeper counterpart, where Hornets and Man Eaters guard the Underground Jungle. The Ocean edges hold Water Chests and coral.
Dig for a specific reward
Each underground region pays off a different trip. The Ice Biome sits below Snow with its own enemies, the Underground Desert is full of fossils and Amber, and the Underground Jungle grows Life Fruit after the first mechanical boss and Plantera's Bulbs after all three. Caverns hide Underground Cabins, and the Spider Nest hides the Webbed Stylist. Granite and Marble caves are short side trips with their own enemies, and underground Glowing Mushroom biomes are the only place to find Truffle Worms. Mushroom Grass resists Corruption and Crimson, though the first Hardmode stripe can still convert plain Stone inside it.
Structures and player-made biomes need planning
The Dungeon's entrance is open, but its deep halls are a planned trip after Skeletron falls. The Jungle Temple's door waits for the Temple Key that Plantera drops. A Graveyard brings night enemies into daylight, while a Town cuts ordinary spawns when friendly NPCs settle together. Meteorites start only after your first Eater of Worlds or Brain of Cthulhu defeat, so breaking orbs alone won't bring them.
Hardmode changes the map under your feet
Drop a Guide Voodoo Doll into Underworld lava to summon the Wall of Flesh, and defeating it turns the world into Hardmode. Two diagonal stripes cut from the Surface to the Underworld: one becomes the Hallow, and the other your world's evil. Each can spread through eligible blocks after the conversion. The Underground Corruption and Crimson yield Souls of Night; Cursed Flames come from World Feeders, Ichor comes from Underground Crimson, and the Underground Hallow yields Souls of Light and Crystal Shards. The boss guide shows where the Wall of Flesh fits in your route.
FAQ
Does every Terraria world have an Aether?
Only worlds created in version 1.4.4 or later generate one. Older worlds never gain an Aether, even after an update.
What is the difference between the Snow biome and the Ice Biome?
Snow is the surface region and the Ice Biome is its cave counterpart. Frozen Chests only generate in the Ice Biome, and Pigrons appear only in infected ice during Hardmode.
Can you build a Glowing Mushroom biome on the Surface?
Yes. Plant Mushroom Grass Seeds on Mud. The Truffle moves into a house in a Surface Glowing Mushroom biome, so a surface patch is the one to build.
Can you explore the Dungeon before Skeletron is defeated?
Yes. The entrance and a screen or two below it are generally safe, but crossing below Surface depth before Skeletron falls summons Dungeon Guardians. They are nearly invincible and usually kill in one hit. Killing one does not unlock the Dungeon.