Go into Zora's Domain as an adult. There is a platform in front of King Zora. Equip the Hover Boots, and slide off of the platform, then Jump while your in air. If done correctly Link will jump repeatedly. There are more places where you can get yourself to continually jump. The easiest is in Lake Hylia. Swim over the the fishing pond house, but don't leave the water. Go all the way to the right of it and go as far as you can and try to climb up onto the hill. If you get it in the right spot Link will jump spastically.