Iggy's Castle is the first castle in Super Mario World. It is also the only castle that must be played in order to beat the game. Like all other castles, Yoshi may not enter. This level introduces the Climbing Nets and their respective cling-ons, and Podoboos. It is also one of the only three levels to use the Layer 3 Smash Sprite - the others being the Forest Fortress and Bowser's Castle.