The Underground Crimson is a Hardmode biome created after the Wall of Flesh is defeated for the first time. It is the underground version of the surface-level Crimson, appearing at and below the cavern layer. Just like the surface Crimson, it is mainly composed of Crimstone and spreads to nearby tiles.
(Old-gen console and 3DS versions) Small pockets of Underground Crimson can be created through the breaking of Crimson Altars, which can convert a single random Stone Block in the world into Crimstone upon destruction.
The Underground Crimson does not suppress the spawn of other underground and cavern enemies. During Hardmode, all enemies killed in the Underground Crimson have a 1/5 (20%) / 9/25 (36%) chance to drop a Soul of Night.
Note: Most characteristics of the surface Crimson also apply to the Underground Crimson. See The Crimson for more extensive information.
This content is transcluded from Biome backgrounds § Underground Crimson.
On the Desktop version, Console version, and Mobile version, the following backgrounds are used. On the Old-gen console version and Nintendo version, the cavern layer background for any other biome the player is in is dynamically tinted red.
(Crimson Ice) Bumpy red ice wall with Blood Jellies and eyeballs frozen within it
- Desktop 220.127.116.11: Added Otherworldy Underground Crimson track from the cancelled Terraria: Otherworld.
- Desktop 1.2.4: Now has its own specific theme music.
- Desktop 1.2.3: Added biome specific stalactite variations.
- Desktop 1.2: Introduced.
- Console 1.02: Introduced.
- Switch 1.0.711.6: Introduced.
- Mobile 1.2.6508: Introduced.
- 3DS-Release: Introduced.