The Guidance of Apollo sub-quest is a part of the Voice of the Night Sky quest in Endless Ocean 2.
Completion Process[]
The quest Guidance of Apollo only requires that the player find the Solar coin; it is located at coordinates A-4 in the Cavern of the Gods, in the corner room of the hall. When they look at it in their collection book, the radio turns on by itself, and a mysterious voice says:
"...the one...who rules the sun...find the coin...cavern...with the same name...inside the cliff...inherit...riches of the north..."
This is the player's cue to go to the Cavern of the Sun in the Zahhab Region. There, atop the turtle skeleton in the very back of the cave, the "Turtle Shell" air tank can be found, which completes the quest.
Notebook Description[]
When the player finds the Solar Coin, the notebook remarks:
"You found the Solar Coin. It seems heavier and more beautiful than any of the other coins. Take another look at it in the collection book."
When the player does as directed, and hears the radio voice, the notebook will update:
"You heard a strange voice from the radio. It seemed to say that there's something in "the cavern that shares the coin's name"."
After the player finds the Turtle Shell tank, the quest wraps up with:
"You found something rare in the Cavern of the Sun."