In Super Mario 3D Land for the Nintendo 3DS, there are a lot of hidden levels that you can unlock, most of which are unlocked by collecting Star Medals during the game.
Here are all of the levels you can unlock in the game, and how to unlock them.
Unlock World Levels
W1-4 – Collect 3 Star Medals
W3-5 – Collect 15 Star Medals
W4-3 – Collect 30 Star Medals
W5-3 – Collect 40 Star Medals
W5-Bowser – Collect 50 Star Medals
W6-5 – Collect 60 Star Medals
W7-3 – Collect 70 Star Medals
W8-3 – Collect 80 Star Medals
W8-Bowser 1 – Collect 90 Star Medals
W8-Bowser 2 – Collect 100 Star Medals
Unlock Special World Levels
To unlock the Special World, you need to clear all levels on World 8, including the hidden levels listed above.
S1-Bowser – Collect 110 Star Medals
S2-Airship – Collect 120 Star Medals
S3-Airship – Collect 140 Star Medals
S4-Airship – Collect 160 Star Medals
S5-Bowser – Collect 180 Star Medals
S6-Airship – Collect 200 Star Medals
S7-Bowser – Collect 220 Star Medals
S8-1 – Collect 230 Star Medals
S8-2 – Collect 240 Star Medals
S8-3 – Collect 250 Star Medals
S8-4 – Collect 260 Star Medals
8-5 – Collect 270 Star Medals
S8-Bowser – Collect 290 Star Medals
S8-Crown – Collect all 290 Star Medals, beat every level as both Mario and Luigi, and get golden flagpoles on every level. Check out my other guide if you need to know how to unlock Luigi.
Note that when it says “collect all 290 star medals”, that does not include mystery boxes. This means, you must collect all 290 star medals hidden in the levels of the game.