Telescope

The telesope is an item Link's sister, Aryll, gives Link in the beginning of The Wind Waker as a birthday present. Although she says she'll let him borrow it for one day only, he ends up keeping it for the rest of the game.

Zuko, one of Tetras pirates, also have a telescope, very much like the one Link gets from Aryll.

In The Legend of Zelda: Phantom Hourglass, one telescope can be received from Imposter Link for a telescope to be given to a member of the Ho Ho Tribe.