Everness
SaKeL

Adds many new biomes, items and blocks.

Wilhelmines Natural Biomes
Liil

Adds 9 new biomes

Wilhelmines Marinara
Liil

adds water structures and coral reefs to the oceans of your world

Wilhelmines Living Jungle
Liil

Adds a new type of dense jungle biome to your world

Wilhelmines Living Floatlands
Liil

Adds various prehistoric animals to your Floatland Zone, if you are using V7 Map Generator.

Livingcaves
Liil

Adds more life to the caves of your world

Noriel Sylvire's Minerals Core Modpack
Noriel_Sylvire

An API for automatically registering recipes, nodes and ore generation.

Nether
PilzAdam

Adds a deep underground realm with different mapgen that you can reach with obsidian portals.

Too Many Stones
JoeEnderman

88 stones that will spawn in most games. Supports English, Español, Français, Deutsch, Pусский, Português, 日本語

Underground Challenge
Hume2

Explore all 62 underground biomes!