Grappling Hook
From Zelda Wiki.org
The Grappling Hook is an extremely useful item that first appears in The Wind Waker. It is a gift from Medli after freeing her from monsters inside the Dragon Roost Cavern. With it, Link can target certain objects and swing to them. He can also use this to lock on and steal any hidden treasure an enemy has hidden. The Grappling Hook was said to have been used by the Rito people before they obtained wings.
When used aboard the King of Red Lions, the Grappling Hook becomes a crane, which allows Link to pull up Treasure Chests from the seabed. These can be found beneath the Light Rings, or by using Treasure Charts.
This item helped pave the way for the Clawshot in Twilight Princess, which is a combination of the Grappling Hook and Hookshot.
The Grappling Hook reappears in Phantom Hourglass. Here, it can be used like a Hookshot, in addition to being tied to two poles to create a tightrope, or to slingshot Link across large holes. It is used to defeat the boss, Gleeok. The Salvage Arm replaces the grappling hook's crane feature at sea.
