Once you gain five Bear Coins, return to Wrinkley's Save Cave. Go to where you went when you started the game. Next to her cave is one of the bears. Go there and he will have a shell and a mirror on sale. Buy the shell. You will now be able to ask the bear about a castle. Ask him about it. He says that he will give you information on it for two coins. Say "No" and he will start talking about Link. He will even mention rupees.
