Telescope

The telescope is an item from The Wind Waker.

Location
Belonging to Aryll, Link's sister, the telescope is her most treasured possession. Despite this, Aryll lends it to her brother at the beginning of the game as a birthday present. Although she says she will let him borrow it for one day only, he ends up keeping it for the remainder of the game after she gets kidnapped.

Uses
It is with the telescope that Link notices Quill looking up at the sky at the giant Helmaroc King kidnapping the pirate Tetra, and it is also the only time the telescope is truly needed to advance in the game. However, the telescope is also useful to locate elements that are too far from Link's first glance, such as the seagulls surrounding a Big Octo, or a submarine.

Kaleidoscope
The Kaleidoscope is the second item from the Phantom Hourglass trading sequence. When Link takes the Hero's New Clothes to The Hero on board the Traveler's Ship in the North Western Sea, he will be given the Kaleidoscope, which he mistakes for a Telescope at first. The Kaleidoscope needs to be taken to the Ho Ho Tribe.

Trivia

 * Zuko, one of Tetra's pirates, also has a telescope, very much like the one Link gets from Aryll.
 * Pink "scout" Bokoblins out on the Great Sea have a similar form of telescope that they use as weapons. Strangely enough, if a pink Bokoblin picks up a weapon, it holds both its telescope and weapon in the same hand.
 * Old Man Ho Ho also has a kaleidoscope which looks similar to the telescope from the outside.
 * The lonely boy Kamo from The Wind Waker makes a habit of staring at the full moon with his telescope.
 * A telescope resembling Aryll's can be seen in the background of Linebeck Trading Company.