Dungeons are a type of structure found underground. They act as a form of progression for the player.
Info
Dungeons have three sections; an entrance section usually found underground, the first dungeon section, which has a giant monster or a boss as the final challenge, and the second dungeon section, which has a giant sword related to the dungeon theme as the final enemy. The Leaf Dungeon actually has four sections, as it has an extra section with the Leaf Fairy. The Fire Castle Dungeon also has an extra section with the Hell Dragon, but it doesn't have a second dungeon section.
Dungeons have several rewards upon finishing one. In the first dungeon section, there is a tiered hammer as the main reward, and a piece of the shadow armor in the second dungeon section as the main reward (the exception is, again, the Fire Castle Dungeon, since that is the only dungeon without a Shadow Armor Piece. Instead, it gives dragon scales upon defeating the Hell Dragon.). Aside from the main rewards, there are also bricks, medallions and potions given as secondary reward.
List of Dungeons
(Listed in order of progression)