Return to King Zora’s Chamber and show the King the letter from Princess Ruto by equipping the Bottle to one of the C Buttons. King Zora will slide himself over revealing a passageway to Zora’s Fountain.
Lord Jabu-Jabu can be found sleeping right near the entrance to Zora’s Fountain. The first area that should be explored in this area though is a small island on the southeast corner of the map. There is a pine tree surrounded by a few shrubs and a Gossip Stone (the one-eyed statue).
Roll into the pine tree to reveal another 
Gold Skulltula (number 29 of 100). You can also use a 
Bomb near the large rock on this island to destroy a huge wall that leads to another Great Fairy Fountain:
In order to save Princess Ruto you will need to get inside Lord Jabu-Jabu’s belly. You can get Lord Jabu-Jabu to open his mouth by presenting him with a fish. You can use one of your empty Bottles to catch a fish.
The easiest place to do this is in the shallow waters near the shop in Zora’s Domain. Use your bottle near the school of fish swimming around until you catch one.
Use the Fish/Bottle item while standing in front of Lord Jabu-Jabu to get inside.
