Golden Scale

In Ocarina of Time, the Golden Scale allows Link to dive deeper than he could with the Silver Scale, giving him the ability to dive 9 meters total. It is obtained by catching a a record-breaking fish at the fishing hole in Lake Hylia as an adult. With it, Link can dive to the bottom of the water in the Lakeside Laboratory and receive a Piece of Heart. The Golden Scale is completely optional and is not needed to complete the game.