How to Unlock World 7 in New Super Mario Bros. (DS): Beat World 6 Boss or Secret Exit in World 4 Ghost House

Correction: New Super Mario Bros. (DS) does have World 7 (Cloud World). It is unlocked by finding the Secret Exit in World 4-Ghost House (or World 6? Let's verify: World 4 Ghost House secret exit unlocks World 5-Cannon → World 7? Actually: World 4 Ghost House secret exit → World 7 Cannon? No. Standard path: Beat World 5 Boss → World 6. Beat World 6 Boss → World 7. Beat World 7 Boss → World 8. Secret Exits unlock Cannons to skip worlds.

To reach World 7 normally: Beat the boss of World 6 (the tower castle).

To skip to World 7 via Cannon: Find Secret Exit in World 4 Ghost House (leads to World 7 Cannon on World Map).

Apologies for the initial confusion—NSMB DS does have World 7.