Return to Molida Island
Now that we have the Sun Key, it's time to return to Molida Island, where we remember seeing a sun-marked door that required a key to unlock. Plot your course toward the island, keeping watch for any monsters and barrel mines that are in your way. Blocking our arrival on the island, though, is a giant Eye Plant monster that will fire green gobs at your ship. Its eye is its only vulnerable spot, though, so have your ship go back and forth in a close half-circle around the creature, firing at its eye when it opens and also firing at the green gobs it hurls your way. After some direct hits, the giant Eye Plant will be defeated, and you can finally dock on Molida Island.
Getting to the Temple of Courage
Now that we're on the island, go back to the spot where you found the secret hideout and dig up the hole to go into it. Now head left and then up to where we found the sun-marked door so we can unlock it. Now go north up the passageway and exit to the surface.
Where we appear, head west and then around in a clockwise circle, slaying Miniblins and Electric Chuchus along the way, then go up the stairs and then across the bridge where we see the giant gate that blocks our entrance to the Temple of Courage (which is where we need to find the third and final spirit). There's a stone tablet to the left of the gate that tells you "only statues can urge the temple door open, so focus their light gaze on it". This means we need to find three statues that look like heads and get them to look in the direction of the gate in order to open it.
The first such statue, if we go back toward the stairs, is on a plateau just southwest of us. Just strike it with the Boomerang, and it will emit a light beam that will strike the temple gate.
Now head back across the bridge again, go east of the temple and then go southeast until we see the next statue, which is facing the wrong way. Strike it with the sword to make it emit its light beam, then use the stylus to rotate the statue until its beam is directed toward the temple gate.
Now go southwest and then a little northwest until two Zora Warriors pop up to fight us. Use the same strategy as you did before with the last one you defeated: strike each of them from behind with the Boomerang to stun them so you can use the sword on him from behind. When they are both defeated, the third and final statue appears. Strike it to make it emit its beam, then rotate it until its beam is directed toward the temple gate. With all three beams touching the gate, it can now open. Go back to the temple entrance and enter it.