Airway is the final area of Bowser's Body that Mario and Luigi explore when the Pump Works is beaten. It is apparently located in Bowser's lungs and trachea. The airway has all of Bowser's DNA and is the place where the Dark Star is fought. In order to progress through the Airway, Bowser must inhale a stream of ice from Blizzard Midbus' snout, and alternate in-between to get to the end of the area. The Dark Star slowly progresses through and takes in Bowser's DNA as it goes through. First, it acquires his fist, then his flame breath (but in a more dark flame than bright red), and finally his shell to ground pound. When the Bros. finally make it to the area where they fight the Dark Star, he has the complete look of Bowser, without the legs. The Emoglobin that hosts The Gauntlet suggests that players that want to level up very quickly should battle the monsters in the Airway.