Crystal Caves, or World D, is the fourth secret world of Newer Super Mario Bros. Wii. It is unlocked by completing the secret exit in World 5-8: Magma Iceburrow. Completing the fortress will unlock a shortcut to World 6-3: Fog Cemetery. However, completing World D-A will unlock a shortcut to World 6-6: Cawcaw Treeway.
Layout
Crystal Caves is a violet cave that has many underground enemies.
Levels
D-1: Swooper Cellar
D-2: Toxic Wigglershift
D-3: Spine Springs
D-A: Carapace Catacomb
D-Tower: Toxic Fortress
Other Buildings
Other Buildings in Crystal Caves:
- Challenge House H can be accessed after completing D-1.
- The Crystal Music House can be accessed after completing D-A.
oxic Fortress