1.12.2 Packs are Temporarily Broken due to the disappearance of Better Underground. This is the second time the author of that mod has pulled it from the site. It is getting very annoying. That mod however makes the underground very nice. I am waiting a bit to see what will happen. Sorry for any inconvenience.

Foundation: Epic Caves is a mini world generation modpack focused on creating huge decorated caves in your Minecraft worlds. Caves you can explore for days. Caves you can build bases in. These caverns, in size, are unlike anything seen since the earliest days of Minecraft, but in look, are far superior.

These packs can be played standalone for a Vanilla+ experience or further mods of your choice can be added.

The main mods controlling the generation are Quark and its experimental cave generation features, which in most installs are off by default. Additional amounts of ores are added in the Quark config for Default generation to make up for the spaces in the world.

A second important mod is the Biome Height Tweaker. It contains an alternative cave generation algorithm that is much like what was used in Beta version of Minecraft.

Not all the mods will be the same across Minecraft versions. An up-to-date list will be kept here.

Epic Caves 1.12.2 Lite Mods
Quark and dependent AutoRegLib
Biome Height Tweaker
Better Underground

Subterranean Waters

Epic Caves 1.12.2 Deocrated Mods

All Lite mods

Minecraft Mineralogy

Cave Root

Lava Dynamics

Epic Caves 1.11.2 and 1.10.2 Lite Mods
Quark and dependent AutoRegLib
Biome Height Tweaker

UndergroundOcean

Epic Caves 1.10.2 Decorated Mods

All Lite mods

UndergroundBiomesConstruct

UBC Ore Registrar

WTF's Expedition

Note: Optifine is recommended for the Decorated versions.

Here is a video demonstrating the 1.12.2 Decorated version of the pack.

About Foundation Packs
Modpacks are great but most experienced players have developed a style of play and core mods that they depend on. Personally, I always end up altering modpacks for this reason. I am usually willing to fight through all the issues I introduce by doing this. It is part of the fun and education.
Foundation packs are intended to contain bare essential mods that create a certain effect or scenario. It is left up to the player to decide what else they want to add. Maybe you want more tech or more magic? Maybe you want tools to build or more decorative blocks? Go right ahead. Mix and match these packs with other mods you like. More packs to come.