Ring of Light

Light Rings are objects in. As their name implies, they are rings of multicolored light on the surface of the Great Sea that mark the location of sunken treasure.

Characteristics
While on board the King of Red Lions, Link can use the Grappling Hook above the point of a Light Ring in order to draw up the sunken chest that lies below. However, Light Rings will disappear if Link moves within a certain distance of them, requiring that he gauge their exact location manually; they also release an audible sound as Link draws closer to them to aid in this process.

Light Rings can lead to a number of different rewards, although the most common are Red and Purple Rupees. Light Rings also appear after defeating certain enemies on the sea, such as Big Octos and Warships. There are certain varieties that only appear at night or during a full moon; the Light Ring Chart can be used to find their locations.

Special Light Rings also appear on the sea after opening a Treasure Chart or Triforce Chart. To differentiate these from the others, a beacon of light is projected into the air from the center of the ring. These Light Rings will also disappear at a greater distance than normal, requiring that Link use their respective charts in order to pinpoint their locations. Their rewards include Silver Rupees, Pieces of Heart, Special Charts, and Triforce Shards.

A large, golden Light Ring appears before the Tower of the Gods, that serves to allow Link beneath the waves to visit the sunken kingdom of Hyrule. Link can only access it at first by reaching the top of the tower and defeating Gohdan, and later on by reassembling the Triforce of Courage.

Trivia

 * When salvaging treasure from a special chart, there is a chance Link will pull up a pot if done in the incorrect spot. Occassionally, doing so will also cause an Octorok to appear nearby.