1. This one's linked to the story, but you can miss it if you aren't careful. After you break the first cage in the area north of the main tree, sing with the eye-flower and it will create two flowery platforms for you. Jump from a rock that's jutting out toward the first flower, then glide from there to the second flower. The crystal will be on a ledge ahead of you, but you won't be able to reach it even by gliding – instead, head toward a tree growing out of the cliffside beside it, then jump to the ledge from there and grab the crystal.
2. Once you've freed the giant deer, glide to where it was standing and grab a crystal floating in a small enclosed pool.
3. Near the southwest part of the area, you'll find an owl perched near a tall rock wall. Sing with the owl and it will drop you off in its nest, where a crystal awaits.
4. Face the rock wall where you got crystal 3, then look to the far-right side. You'll just be able to see a crystal through a small gap in the rock. Crawl through and it's yours.
5. After you leave the crag where you found crystal 4, run beside the rock wall to the west until you reach a huge pile of boulders at its southern end. There's a gap between the two boulders closest to the wall, covered by a Silent One cage. Head east, hugging the rock wall, until it ends. Run around the edge of the wall and you'll find yourself in a familiar place, where you used bomb seeds to help free the giant deer. Grab a seed from the nearby plant and head back to the gap in the boulders. One good chuck and the crystal inside is yours.
6. Once you can speak the deer language, go to the top of the rock wall where you found crystal 3 and sing to the float flower there. Float up on the flower’s updraft, then glide north toward a rocky outcropping with a crystal on it, activating other float flowers along the way to give you lift.
7. Head to the far northeast corner of the map, to what looks like the entrance to a large clearing off the main area. You'll be greeted by a rock wall with a small gap in the top – use the nearby trees and rocks to reach the gap and float through. On the other side, you'll find a large tree with float flowers growing inside. Use them to reach the top of the tree, then carefully glide over to a line of other float flowers on rocks jutting out of the cliff. At the end you'll find a nice, large platform with a crystal perch regally on top of a rock.
8. Head toward the west side of the loop at the area's north end, and you'll find a large rock jutting out of the cliff with some smaller rock formations beneath it. Drop to the ground and crawl through the rock formations, and you'll find a crystal hidden inside.
9. After you break the last cage to free the giant deer, sing with the eye-flower and it will create a bouquet of platform flowers immediately to the west. Bounce off them to the ledge above and grab the crystal waiting there.
10. In the northeast portion of the area, you'll find several trees growing up a rock ledge supported by a blocky pillar. Jump from tree to tree to reach the ledge and look across the gap to see a crystal nearby. The tangle of rocks ahead of you can look intimidating, but you don't have to worry about them at all. Turn around and climb up the wall of blocks behind you, run to the end, then jump and glide to the crystal platform.
11. You can get this crystal before or after the Silent Ones have left the area, depending on how sneaky you are. At the opening of the canyon, drop down to the lowest level and head toward the sheer rock wall in front of you. As you get closer, you'll see a gap to the left of the wall – go inside and you'll find the crystal waiting.
12. As you enter the deer's domain through the northeast passageway from the Great Tree Valley, you'll spot a tree leading up to a series of spring flowers. Bounce your way up the cliff to a small alcove with a bomb plant and several spring flowers in Silent One cages. Simple enough, but there's one problem: there's a bear between you and the bomb seed. Dodge carefully around/frantically run from the bear with seed in hand, and after you free the first spring flower, throw another seed into the flower itself to rocket it up to the last trapped flower. Then it's just a hop, skip, and a bounce to the crystal on the ridge above.
13. You can only get this one after you've beaten the game. Enter the deer's domain from the northeast passage, then head south to a path bordered by giant orange rib bones. Climb up to the spring flower, which will deposit you at the mouth of a vertical shaft. If you've beaten the game, you'll see two jellyfish inside. You know what to do: use them to launch yourself upward and claim the crystal you find above.
14. You may have spotted this one early in the game (with no idea how to reach it), but it's only after you learn Fe's last language that you can finally claim it for yourself. After you've completed the game, enter the deer's domain from the northeast passage from the Great Tree Valley. When you reach the first gap, climb up the tree in front of you, but then take a closer look ahead: two jellyfish creatures are now floating above the chasm. Sing to them, then glide to the second one and have it shoot you toward the crystal ledge (not straight up – you'll hit a branch and go tumbling back down). Finally, this crystal is yours.
15. After you interact with the jellyfish creatures for the first time, follow the path they've created for you until you see a platform with several spring flowers on it. Launch out of the last jellyfish to the first spring flower, then jump from flower to flower until you reach a crevice with a crystal inside.