World 6 (Super Mario World 2: Yoshi's Island)
From the Super Mario Wiki
World 6 (also known as the Koopa Kingdom) 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, resembling the landscape and environment of Yoshi's Island. The world contains eight normal levels and one (or 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
Names in other languages