Hyrule's underworld is made up of nine labyrinth dungeons. The entrance to some dungeons, particularly the earlier ones, are right out in the open, while some require a step or two to expose. Each labyrinth is in a particular shape, be it an object, symbol, or even a letter of the alphabet. Unlike the Overworld, the underworld of the second quest differs drastically from that of the first quest.
- Most items that you can find in the dungeons can only be obtained when you defeat every monster in a room. The only monsters that do not count are bubbles or traps, which can not be beaten. Therefore, it is in your best interest to clear every room at least once if you are trying to maximize your collection.
- Doors which are not open or locked, but rather shut with a diamond pattern printed on the door, can only be opened either by defeating every monster in the room, or by pushing certain blocks in the room after all of the monsters are defeated.
- Blocks which must be pushed in order to open doors, or reveal staircases, can only be pushed once every monster in the room is defeated. The block to push is usually the first block from the left along the center (fourth) row of a dungeon room.
- If you unsure of how to proceed through a dungeon, be sure to bomb every wall that you encounter which does not contain a door. You will typically find passageways that lead further in to the dungeon. It is also not uncommon to find passages to rooms in the "eyes" or unmarked rooms on the dungeon map.
- In the second quest, it is also possible to walk through certain walls that are simply illusions. To do so, push against the wall until access to the room beyond is granted.
- When fighting against monsters, Link is capable of swinging his sword upwards through a block, and still hit a monster directly above the block on the opposite side. He can not do this in any other direction other than up.
- Another useful tactic when fighting monsters is using the ladder to position yourself safely on water where the monsters are incapable of reaching you. This is particularly effective against Darknuts, but completely ineffective against blue Wizzrobes who can still collide in to you while levitating over the water.