World Overview
The biomes and structures that matter, and how each one maps onto the boss-gated progression from the Forest to the Underworld to the Hallow.
A Terraria world is a fixed set of biomes and structures, and almost every one is tied to a step in the progression spine. You do not explore for its own sake; you explore because the next boss, ore, or unlock lives in a specific place. This page is the map of where things are and when each place becomes relevant, so you know why you are going somewhere before you dig.
What every world contains
Every world always generates the same core set: a Forest, two Oceans at the far edges, the Dungeon, the Underworld at the bottom, one evil biome (Corruption or Crimson, never both), the Underground Jungle, and a Glowing Mushroom area underground. Biomes generally exist in surface and underground or cavern variants. The Hallow is the exception: it does not exist until Hardmode.
The key mental model is vertical layers stacked from Space at the top down to the Underworld at the bottom, with surface biomes spread horizontally across the middle.
The early-game surface
The Forest is the default starting biome, with mild enemies and the space for your first housing. This is where you build the valid houses that attract the Merchant, Nurse, and Demolitionist, and it stays your home base for most of the run.
The two Oceans at the map edges are fishing biomes. They matter later for the Truffle Worm (bait for Duke Fishron) and the Angler NPC’s quests, but early on they are mostly a landmark. Floating Islands and Sky Chests sit up in Space above the surface, holding useful early loot if you can reach them.
The evil biome and its meteor
Your world has exactly one evil biome. Corruption is a dark purple biome of chasms, Shadow Orbs, and Ebonstone, home of the Eater of Worlds and the source of Demonite and Shadow Scales. Crimson is the red, flesh-themed alternative with Crimson Hearts and Crimstone, home of the Brain of Cthulhu and the source of Crimtane and Tissue Samples. You fight whichever you have.
Breaking a Shadow Orb or Crimson Heart can trigger a Meteorite crash site to appear, which contains Meteorite ore for the mage’s early Meteor armor and Space Gun combo.
The Jungle, Dungeon, and Underworld
Three places anchor the mid and late game:
| Place | What it holds | When it matters |
|---|---|---|
| Underground Jungle | Bee Hives (Queen Bee), later Plantera’s Bulbs, Chlorophyte ore, and the Jungle Temple with Golem | Pre-Hardmode through post-mechanical |
| Dungeon | Guarded until Skeletron dies. Unique loot, and after Plantera the Cultists and tougher enemies | After Skeletron, then again after Plantera |
| Underworld (Hell) | Lava, Hellstone, Shadow Chests. Where the Wall of Flesh is summoned | Late pre-Hardmode |
The Underground Jungle is the single most important place in the world because so much progression routes through it: Queen Bee early, then Chlorophyte and Plantera in Hardmode, then Golem in the Jungle Temple. Protect it from biome spread.
The Snow and Desert
The Snow biome and its Underground Ice variant hold Deerclops (during a Blizzard) and ice-themed loot. The Snow biome is also the community-favorite spot for happy NPCs: Mechanic plus Goblin Tinkerer there gives the cheapest reforging in the game. The Desert has a dangerous Underground Desert full of hardened sandstone, Antlions, and unique loot.
Hardmode: the Hallow
Killing the Wall of Flesh generates the Hallow, a pastel rainbow biome that did not exist before. It contains Pixies, Unicorns, and an Underground Hallow with Crystal Shards and the Gelatin Crystals that summon Queen Slime. The Hallow counteracts the evil biomes but also spreads.
All three contagious biomes (Corruption, Crimson, Hallow) spread to adjacent susceptible blocks over time. Spread rate halves once Plantera is defeated, but before that it can eat your Jungle and base. Dig trenches or use the Clentaminator to contain it early in Hardmode.
How it maps to progression
The short version: build in the Forest, dive the evil biome for your first ore, open the Dungeon via Skeletron, mine Hellstone in the Underworld, and summon the Wall of Flesh there. In Hardmode, the new Hallow and the Underground Jungle become the centers of gravity: Chlorophyte and Plantera in the Jungle, then the Jungle Temple for Golem, then back to the Dungeon for the Cultists and the road to the Moon Lord.
Next: for the fight that transforms this whole map, see the Wall of Flesh deep guide. For the order of every boss and unlock, see the boss order cheatsheet.