As soon as you enter Zora's River, bomb the boulders blocking your path. Up ahead you will find the magic bean seller, you can buy up to 10 magic beans from him. First one is 10 Rupees and each one doubles after that! You should have a full Giant's Wallet . Grab the chicken near the ring of rocks and float over to the other side of the river. Continue up until you are on the left side and you find yourself beside a log. Carefully walk to the edge of the log, and take out your ocarina. Some frogs will pop out of the river and ask you to play for them. Play all the songs you know. When all five of them become big, they will give you a piece of heart. Now continue up the river until you find a small bridge. Cross the bridge and go around the corner to the giant waterfall. You will find you have to jump from one platform onto one below. Walk up until you find the triforce crest and play Zelda's Lullaby. The water will stop flowing, allowing you to enter Zora's Domain.