Make sure you have at least one Bomb Arrow before you tackle this quest.
Find Kass at the Horon Lagoon, south east of Zora's Domain. He sings you the following song:
"He breaks the rocks that serve to bind, above the tempestuous bay. On wings of cloth and wood entwined, he lands on the altar to open the way."
This is one of the simpler riddles to figure out (obviously, you'll be breaking some rocks and using your glider) – but we'll admit this quest took us more than one attempt to get done.
Where we went wrong was smashing just a couple of the rocks and thinking we'd be able to glide to the altar from the resulting thermal drafts.
You'll need to find and break all the breakable rocks in the area, and the game will let you know when you've done so – the camera will pull away to show you the altar starting to glow orange.
You can't just glide to the altar from anywhere, so head over to this rock to start the glide. Land on the altar to reveal the Shai Yota shrine.
This is another blessing, so there's no puzzles or Guardians inside, just a chest containing a Great Flameblade – a two-handed sword with 34 attack points with the added bonus of dealing fire damage.