The Cave Planet Cavius (originally Cavios) is the cavern star from Milky Way Wishes and exists in a galaxy near Planet Popstar. It is the fifth planet, following Hotbeat and preceding Mekkai; however, because Milky Way Wishes is a non-linear game, it can be played at any time. The surface of Cavius is mountainous, but it also has many craters. Its first main area is a mountain, which leads to a system of caves that contain rooms with all the mid-bosses faced until that point in the game. Near the core of Cavius is a large water reservoir.
Stone: After the room filled with Mid-bosses, destroy the Bomb Block to release the water. Go into the water pool and press the Switch to the right. Go back down and enter the door the was obstructed by a gate.