One secret room per floor
A floor usually hides one secret room. It has no door, so you reach it by bombing a wall.
That room can hold pickups, an item, or coins. The reward varies, but the cost is one bomb.
Where the wall is
Secret rooms touch the normal rooms around them. The wall between them looks solid but can break.
Look for a gap in the map shape. A hole next to a room often marks where the secret room sits.
How to test a wall
Bomb a wall you suspect and watch for the break. A normal rock clears; a secret wall opens a passage.
Try the wall next to the most rooms first. Corners shared by a few rooms are common hiding spots.
Super secret rooms
A deeper floor can hide a super secret room. It sits farther from the center and needs its own bomb.
These rooms tend to hold a stronger reward. Weigh the bomb cost against the risk of finding nothing.
Next: Keys, bombs and pickups and Floor routing.