Cavern

The change of background that marks the beginning of the Cavern layer.

The Cavern layer is the largest layer, beginning just below the Underground and extending all the way down until the Underworld layer. It is characterized by darker stone background tiles. Stone is the predominant block in this layer (as opposed to Dirt in the Underground). Caverns contain occasional Underground Cabins where valuables can be found, as well as Mushroom Biomes, dangerous traps, rare and dangerous Spider Nest mini-biomes, and much more.

Lava begins to appear around -2100ft in small pools, which gradually become lava wells at around the -3000ft mark.

Map Size	Min Start Depth	Average Start Depth	Max Start Depth
Small	120 ft	480 ft	840 ft
Medium	180 ft	720 ft	1260 ft
Large	240 ft	960 ft	1680 ft

Contents

Map view highlighting the Cavern layer range

Characters

• Black Slime
• Mother Slime
• Baby Slime
• Giant Worm
• Skeleton
• Cave Bat
• Salamander  
• Crawdad  
• Giant Shelly  
• Undead Miner(uncommon)
• Vampire Miner 
• Tim(rare)
• Nymph(rare)
• Pinky(rare)
• Cochineal Beetle(uncommon)
• Mouse

In Water:

• Blue Jellyfish
• Piranha

In Spider Nests:

• Wall Creeper

In Hardmode:

• Digger
• Giant Bat
• Armored Skeleton
• Skeleton Archer
• Rune Wizard(rare)
• Ghost (enemy)(during Halloween)

In Water in Hardmode:

• Angler Fish
• Green Jellyfish

In Spider Nests in Hardmode:

• Black Recluse

Traps:

• Dart Trap
• Boulder
• Explosives(rare)

Unique Drops

From Giant Worms and Diggers:

• Whoopie Cushion(rare)

From Cave Bat:

• Chain Knife(uncommon)
• Depth Meter(uncommon)

From Vampire Miner and Undead Miner:

• Mining Shirt(uncommon)
• Mining Pants(uncommon)

From Undead Miner:

• Bone Pickaxe(rare)

From Vampire Miner:

• Vial of Blood 

From Tim:

• Wizard Hat(always)

From Nymph:

• Metal Detector  (50% / 100% chance)

From Cochineal Beetle:

• Red Husk   

From Skeleton:

• Ancient Iron Helmet(rare)
• Ancient Gold Helmet(rare)
• Bone Sword(rare)
• Skull(very rare)

From Armored Skeleton:

• Beam Sword(rare)

From Skeleton Archer:

• Magic Quiver(uncommon)
• Marrow(uncommon)

From Rune Wizard:

• Rune Hat(always)
• Rune Robe(always)

From terrain:

• Enchanted Sword(extremely rare)
• Arkhalis  (incredibly rare)

From Fishing:

• Scaly Truffle   (specific conditions)

History

 Desktop version

• Desktop 1.3.2: Geysers now spawn as traps.

• Desktop 1.3.0.1:
  • Marble and Granite Caves can now be found anywhere in the cavern layer.
  • Detonator traps added.

• Desktop 1.2.2: New "Alternate Underground" soundtrack.

• Desktop 1.2: Enchanted Sword (item) can now be found as a rare drop from the terrain.

• Desktop 1.1: Random traps added.

• Desktop-Release: Introduced.

 Console version

• Console-Release: Introduced.

 Switch version

• Switch 1.0.711.6: Introduced.

 Mobile version

• Mobile-Release: Introduced.

 3DS version

• 3DS-Release: Introduced.