The underground is a mod that adds a new dimension to the game, called Betweenlands. Although it is not a dimension with four new things. It is a complete dimension, with a large amount of new content, which will present us with new adventures, full of new challenges.

The Entreterres are the remains of an ancient civilization lost in time. It is a dark and mysterious realm, inhabited by monstrous creatures that live among the remnants of what was once a mighty realm.

In this new dimension we can find a good amount of new biomes, trees, flowers, materials and minerals. We will also find dilapidated structures, such as fortresses and underground ruins inhabited by strange hostile creatures. Not to mention new crops, over 300 new building blocks, over 350 new items, 250 new sounds, random weather changes and supernatural events.