World 3 is the third world that Mario and Luigi venture through and has a beach-like theme with many beach and underwater levels. Bowser Jr. serves as the mini-boss here for the third time and the boss here is Cheepskipper. This place possibly may be the home to Cheep-Cheeps and this world also introduces and has the first Ghost House in the game. This world isn't required to complete the game, instead Mario and Luigi can venture through World 4 to advance to World 5.