Vanilla Dome, the third world of SMW, is located inside the mountain north of Donut Plains and west of the Twin Bridges. It features both an interior and exterior set of levels. The interior set is primarily cave-themed, and features the normal route of levels. The secret route goes to the exterior set, which eventually leads to the first Fortress in the game. Vanilla Dome also has a Star World warp hidden behind a secret exit.
This world is tied with Donut Plains for the most stages at 11. However, where the plains has 15 exits, Vanilla Dome has only 14.
Vanilla Dome contains the following 11 levels:
|11A||Vanilla Dome 1|
|118||Vanilla Dome 2|
|11B||Red Switch Palace|
|107||Vanilla Ghost House|
|10A||Vanilla Dome 3|
|119||Vanilla Dome 4|
|109||Vanilla Secret 1|
|001||Vanilla Secret 2|
|002||Vanilla Secret 3|
|11C||#3 Lemmy's Castle|
- The Red Switch Palace is a Special Message Level. This can be changed using the Overworld Editor, should you choose not to use level 11B for the same purpose.
- Vanilla Ghost House is one of two Ghost Houses without a secret exit.
- Vanilla Fortress is the only castle level set underwater.