The Crystal Cave
The cave entrance was a small hole in the ground, barely seen from the surface due to it being covered by tallgrass. If not for [Mark] I would have traversed the tall grass for days and likely starved to death before I found it.
I watched the steady progress of the mimics with [Labyrinth Atlas] as they descended the deep cave entrance. The part of the map that used to be dark lit up as their scurrying paths diverged to illuminate the cave's entire tunnel system.
It was a multi-layered with many channels branching out from where the opening began, before leading to a central cavern below that was about a quarter of the entire grass field.
I was pleased to see that, much like a creature's burrow, the mimics did not exit through any other opening in the ground, which meant there was only one entrance.