Dark, browny, calm place. Located in a river, but it is called Inside Rivers because there's a huge tunnel covering it. At the bottom-right corner, you will see the actual paths of the track. There's only one, quite long path, but it's called devastatingly master track because you can't attack the bloons while they're going into the tunnel, and the time the bloons will go out of the tunnel is short. There's water, but you can't build in rivers because it serves as pathway of bloons.