The "Burrows" is the name given to the sprawling underground tunnel system inhabited by members of the faction known as "The Den". The faction is run by Ina, and is exclusive to smaller species like Kitsune and Spiders. The Burrows are divided into multiple well maintained tunnels made of luxurious wood, with dozens of inhabitants living within small cutouts in the walls in all directions, just like a real Burrow.
Some of the wings include a Lounge, Storage area (with a dedicated ME system), and a public nature reserve in the center. There is also an abandoned wing that can be seen, but is fenced off. Signs border the fences claiming that the area is extremely hazardous, and a unknown mind-altering chemical lingers in the unfiltered air that resides within its chamber. From the fences however, it looks like nothing more than an overgrown wing of the base, almost like a forest.
It is said that Ina treats this forest as a home, and is unaffected by whatever the Chemical is... if it even exists.