Donut Plains is the second world Mario visits in Super Mario World. The plains introduces the concept of secret exits and features multiple possible pathways to Morton Jr.'s Castle. Also featured are the first instances of the Feather, the Ghost House, and the Star World warp. Donut Plains is also tied for the largest world in the entire game. Both this world and the next, Vanilla Dome, have 11 stages (though Donut Plains has 15 exits compared to Vanilla Dome's 14).
Donut Plains contains the following 11 levels:
|015||Donut Plains 1|
|009||Donut Plains 2|
|008||Green Switch Palace|
|004||Donut Ghost House|
|003||Top Secret Area|
|005||Donut Plains 3|
|006||Donut Plains 4|
|00A||Donut Secret 1|
|013||Donut Secret House|
|10B||Donut Secret 2|
|007||#2 Morton's Castle|
- The Green Switch Palace is a Special Message Level. This can be changed using the Overworld Editor should you choose not to use 8 for the same purpose.
- The Donut Secret House is a Boss Sequence Level - that is, upon defeating the Big Boo boss, the secret exit is activated. This can be changed using the Overworld Editor should you choose not to use 13 for the same purpose.
- There are some unused levels, both called "#2 Morton's Plains," located on the Yoshi's Island part of the Main Map. They are levels 017 and 019 in Lunar Magic and look like Iggy's destroyed castle and Yoshi's House, respectively. Level 017 is Donut Plains 1 with a garbage background, and level 019 is just a test level. One wonders why it was necessary to assign these tiles level addresses at all.
- The cutscene that plays after you defeat Iggy Koopa incorrectly refers to Donut Plains as Donut Land.
- In a speedrun, it is possible to skip from this world to the end via the Star World. The player does not have to defeat any of the Koopa Kids except for Iggy.