The Legend of Zelda/Underworld/Quest 1/Dungeon 5

Objectives

 * Obtain the whistle.
 * Expand your bomb carrying capacity.
 * Defeat Digdogger.
 * Obtain a heart container.
 * Obtain the fifth Triforce piece.

Walkthrough

 * To enter this dungeon, you must discover the secret to climbing to the top of the Lost Hills.
 * From the entrance, go right and clear this room to obtain a key. You may bomb the top wall to expose a passage to the man with information about this dungeon's boss's weakness.
 * Enter the room above the entrance and defeat the Gibdos for another key. You may bomb the left wall to provide yourself with a shortcut to the left which bypasses the Dodongos.
 * If you enter the room above, you must face three Dodongos. Defeat them in the usual manner, either feeding them two bombs, or stunning them by exploding a bomb in their face.  If you unlock the north door, you can obtain the dungeon's map.
 * From the Dodongo room, enter the left room, and obtain a key. Then enter the room below and defeat the Gibdos.  To access the room to the left, you must bomb the left wall.
 * Enter the left room and defeat all of the Darknuts. When the room is clear, push the leftmost block aside and enter the stairwell.  Take the passage, and you will arrive in the right top most room of the dungeon.
 * From there, head left and defeat all of the Darknuts. When the room is clear, push the single block to reveal a stairwell that leads to the whistle.  Collect the whistle and return to the right.
 * Now head to the room below, and collect a key. Bomb the right wall to discover a passage to a room where a man will add four bombs to your bomb storage capacity for 100 rupees.
 * Return through the underground passage, and back to the room with three Dodongos.
 * From the Dodongo room, head right, and then above to collect another key. Head up again and defeat the Darknuts to discover the compass.
 * From the compass room, head up and obtain a key. Head left, and defeat the Gibdos to receive another key.
 * Head left once more and you'll encounter the Pols Voices. The top wall can be bombed to reveal a path to a man who is knowledgeable on the weakness of Pols Voice.
 * If you head left, you will encounter the boss. There is a room below the boss room that contains nothing but Gibdos.

Boss

 * The boss is Digdogger. While large, Digdogger is invincible.  You must collect the whistle in this dungeon in order to defeat it.  Blow the whistle and it will shrivel up in to a tiny version of itself, which can be stabbed by your sword.
 * Defeat it to earn a heart container. Continue on to the room above to obtain the fifth piece of the Triforce.

Resupply
Dungeon 5 is isolated, and as such, you may want to look at the supply points before heading to the dungeon.
 * A medicine woman is 4 screens west and 1 screen south of the Lost Hills.