The deeper dark biome is the main biome and most common biome in the dimension. It is very similar to the deep dark in the overworld, but with a few key differences. It has more sculk, fossils that contain diamonds, blue fog, sculk traps, and ancient villages. All overworld ores will spawn here, including emerald ore. All other biomes in the deeper dark are variants of this biome except the deep oasis.

The deeper dark cavern biome is almost identical to the deeper dark main biome except instead of small caves, the biome is a large cavern, and the only structures are ancient fortresses.

The volcanic caverns biome has basalt pillars, lava, magma blocks, gravel, tuff, and ancient debris. It is very similar to the basalt delta biome in the nether. At the center of the biome is a lava river/ravine.

The amethyst mines biome is covered in amethyst, calcite, and smooth basalt. On top of amethyst blocks, you can find calibrated sculk sensors. Since they are on top of amethyst blocks they will signal to other sensors and shriekers, and even cause chain reactions, but sculk sensors and shriekers spawn less frequently in this biome. Various mining suplies can be found around the biome. The only structure here is the amethyst mineshaft.

The deep oasis is a calm sculk-free biome that spawns at the top of tall caves. Many plants live here, and giant vines hang down from the ceiling. sniffers and their plants will spawn here in sniffer nests; geode shaped caves made of moss and coarse dirt. Underneath this biome there are more shriekers than elsewhere in the deeper dark. No structures spawn in this biome. Credit to peA_sh0ter for helping me design this biome.

The ancient dark is the original home of the sculk. The biome is a large cavernous biome, with thin pillars and ledges. It is surrounded on all sides by an Obsidian Barrier The terrain has been completely converted to sculk several blocks deep and bone block stick up from the from the ground and hang down from the ceiling. The bottom of the biome has lava lakes with soul sand beaches. The biome has red fog and red-tinted water. The sculk in this biome is more advanced. In the ancient dark, sculk is also touch-sensitive. Touching any type of sculk alerts the biome and starts spawning wardens. Unique sculk blocks spawn here with unique abilities. This biome is extremely dangerous. The only structures here are laboratories.

The obsidian barrier is the wall of obsidian that surrounds the ancient dark.

Ancient villages are structures similar to ancient cities, but smaller. They are found in the deeper dark biome. They can have a portal in the center, or just a block of reinforced deepslate.

Ancient Fortresses are massive castle-like structures found in the deeper dark cavern biome. They have a portal in the center, just like ancient cities. They have tall walls with many pathways inside them, the loot contains potions and other combat equipment, as well as resources like wood and food.

Sculk traps are the 'spawner dungeons' of the deeper dark. Sculk traps consist of a disk of deepslate bricks supported by 4 pillars, on top there is a barrel, with 2 sensors and 2 shriekers next to it. The loot contains enchanted books, experience bottles, and an enchanted book with one of the first 4 new sculk-enchantments. They spawn in the volcanic caverns and deeper dark biomes.

The amethyst mineshaft spawns in the amethyst mines and can be found using an amethyst mineshaft locator compass. It is a series of wooden mineshaft tunnels connected to a stone center room with a staircase leading up to the top room. The top room has a domed ceiling, 4 side rooms, 4 hallways for housing, and a sculk conversion pedestal on top of the staircase. The 4 side rooms include a room with blast furnaces and chests, a room with a farm, a room with an animal pen, and a room with an auto respawn anchor and reinforced deepslate. There is a lot of loot in these structures, but be careful, there is a new mob in the mineshafts: The Shockwave. One shockwave is found on each floor (except the top room) and will stay on that floor. Shockwaves are really loud, strong, move really fast and wander around their floor. If you see or hear one close by, you need to go to a wall and surround yourself in blocks and wait for it to pass. Each floor of the mineshaft has an altar fragment, you need at least one to create a sculk converter, but you need 8 to fully power it.

The Laboratory if found in the ancient dark and can be found using a laboratory locator compass. It is made out of many rooms with various experiments around the outside, and tunnels on the inside. The structure is very damaged, and is likely hiding something.