World 6 is the sixth world that Mario and Luigi venture through in New Super Mario Bros. This world features many mountain and rock-like levels in this game that Mario and Luigi venture through. This world is the only world in New Super Mario Bros. that features Chain Chomps. This world has two towers and is one of the two worlds to have two aside from World 8. Like the other worlds, Bowser Jr. is fought here and the boss here is Monty Tank.