Donut Plains is the second world, and the first real challenge that awaits adventurers through Dinosaur Land. Whereas Yoshi's Island served as an introduction on how the game works, Donut Plains tests your skills in this game and gives you a glimpse on future foes and enemies you may encounter as you continue through the game.
Donut Plains contains levels that have secret exits, allowing you to take alternate paths through this world. It also contains a well-hidden uplink to Star World, a world that links various areas of Dinosaur Land together. The castle is inhabitated by Morton Koopa, and beating him will grant you access to Vanilla Dome.