The Arena takes place underneath a strange tree. The tree has stretched out its roots underground and grown many circular tunnels where the roots are the walls and there are organic doors leading one tunnel to another which creates a maze of sorts. Oxygen and light is provided from glowing fungi growing within the tunnels, humidity is high and it is recommended for those who are combatants in these tunnels to watch where they attack as the walls and doors are alive. The tunnels are separated by organic doors which will open automatically for you when you approach them but that will cease if you damage the tree too much and attempts on your life may be made if you damage the tree even more (such as the caving in of the tunnel you are currently in). Obviously using fire isn't recommended but only because it will not be too useful. The fungi do not produce that much oxygen too quickly and using fire will quickly create a absence of oxygen in the area you are in. Oxygen levels can return to normal in those areas but it will take time
The tunnels span into a area of 400m in length and 200m in width and 60m in height. There are about twenty floors, however, it is very difficult to make out what floor you are on as you arrive on these floors through overslaping tunnels. The tunnels are all circular and two metres in height (may be altered depending on combatants size) to give a claustrophobic feel. It is generally damp and murky which doesn't help footing and a organic door is always found within the length of 30m to 40m from the last organic door of the tunnel. 20m to 30m of a last branch.
As there is a large amount of fungus in the tunnels a horrid pungent smell fills the air.