The Underground is a mining void that was added by Justin 393 on the 15th of November, 2015.
The Underground is a vest, vigorous terrain that is primarily made up of Stone, Cobblestone & Cobblestone Stairs, Obsidian, Black Hardened Clay, Andesite, Diorite, Granite, and Lava Rivers. The terrain is dangerous, but the reward are tremendous, if you get lucky like brandonross.
The Underground also has it's own version of Abandoned Mineshafts, and are filled with every type of Ore (including Emeralds), and look much more powerful than the ones in the Overworld.
GymSock17 discovered that when you plant a tree in The Underground, that it will take a very wild look that does not spawn naturally in the Overworld.
Within 15 minutes of Justin posting the existence of the dimension, brandonross quickly opened a gate and entered, being the first non-staff person to travel there. Soon, GymSock17 opened his own portal a few minutes later and set up a camp he calls Far Base One.
Brandon was the first to discover a large mineshaft in a cave, and claimed to have found hundreds of Emeralds, over half a stack of Diamond Blocks, and 3 1/2 stacks of Iron Blocks.