Zelda's Indestructible and Unbreakable Treasure Chest is a small blue chest made out of wood. It had a golden Triforce on it, because everything from Hyrule apparently has a Triforce on it. Like it's name suggests, it is indestructible and unbreakable.
Zelda's treasure chest has been used by royalty for generations. It is used to keep people away from evil and powerful items. It is currently being used to contain the Fierce Deity's Mask.
The Chest's Lock
The chest's lock can only be unlocked if someone says the certain key words to it. The words are in Hylain (a.k.a Latin), so they are very hard to pronounce.