AbyssalCraft adds a couple of new biomes to the game, including 7 overworld biomes, 1 Abyssal Wasteland biome and 4 Dreadlands biomes.
Darklands - purple/indigo grass plains-esque biome with some trees and random generated structures. Depths Ghouls and Abyssal Zombies spawn here. Abyssalnite can be mined here, which counts for all Darklands biomes.
Darklands Plains - plains version of the Darklands, has about the same amount of trees as a normal plains would.
Darklands Forest - Darklands biomes with greater amount of trees.
Darklands Highland - An elevated Darklands biome, filler blocks are Darkstone in this biome.
Coralium Infested Ocean - An Ocean biome with murky water and higher rates of Coralium ores.
Abyssal Wasteland Biome
Abyssal Wasteland - barren green wasteland with pools of Liquid Coralium and 100 block tall pillars of Obsidian. All vanilla undead mobs (except Zombie pigmen ), along with Depths Ghouls, Abyssal Zombies, Skeleton Goliaths and occasional Spectral Dragons spawn here. Liquified Coralium Ores (used to obtain Refined Coralium Ingots) can be mined here.
Dreadlands - barren red wasteland biome with Abyssalnite Golems /Dreaded Abyssalnite Golems spawning. Dreaded Abyssalnite and Dreadlands Abyssalnite can be mined here, which counts for all Dreadlands biomes.
Purified Dreadlands - Dreadlands biome with large areas of Abyssalnite Stone (what the Dreadlands originally was made out of, before Cha'garoth).