These are the main collectibles found in each dungeon.
Small Key
Description: This small gray key unlocks doors. It’s always a relief to find one of these. After collecting a small key, press 
while standing in front of a locked door to open it.
Location: Small keys are found throughout dungeons in chests, or out in the open.
Big Key
Description: This large golden key opens the big door to a boss’s room. Press 
to use the Big Key in the big door.
Location: Link finds one of these in a big chest in each dungeon. Finding a Big Key means it’s time for the boss battle.
Compass
Description: A compass makes all unopened chests in a dungeon appear on the map. No more hunting blindly for chests, once you collect this useful item.
Location: Every dungeon contains one of these in a chest.
Heart Container
Description: A full heart container automatically adds one heart to Link’s life gauge.
Location: These drop as your reward for defeating a boss.