World 6 (Super Mario World 2: Yoshi's Island)
From the Super Mario Wiki
World 6 is the sixth and final world of the game Super Mario World 2: Yoshi's Island and its remake Yoshi's Island: Super Mario Advance 3. The world takes place in Bowser's domain, though it include the landscape and environment of Yoshi's Island. The world contains eight normal levels and two secret levels. Its mini-boss is Tap-Tap the Red Nose; the main and final boss is Baby Bowser. This world includes many dangerous obstacles, including lava and spikes, the world's theme is a barren landscape in sunset/starry night sky.
List of Levels