The Shovel can be purchased from the Town Tool Shop in Mabe Village for 200 Rupees in Link's Awakening. It is used to find the Slime Key at the end of the Pothole Field. It can also be used to find some of the Secret Seashells which are scattered across Koholint Island. It, among other items, can also be traded at the end of the Trading Quest to obtain the Boomerang.