a second bomb bag

if you buy a bunch of water bombs, and but on your zora armor, and make your way to the zora's trhoan room where you melted the ice with the volcanic rock and dive down, and down.. and down.. youll see the rock.. swim around it untill youi fint a crack that two eyes are peeking through...there is a small ledge in front of the crack.. stand on it using your iron boots and pull out a water bomb.. blow apart the rock to find a goron that was stuck inside.. he will give you a bomb bag as a show of his thankfulness...