Kah Okeo Shrine
Grab the Korok Leaf from the chest, and use it on the windmill to open the gate. Run through the gate quickly before it closes.
Ignore the explosive barrel and go kill the Guardian Scout IIs in the next room first. They are on the lower level, so drop down.
Now climb up and use the leaf on the windmill to make a balloon-carried platform appear. Hop on it and use the leaf in the direction you want to go to move it. Ride the balloon platform backward to find a treasure chest on a ledge in the corner that contains a Gold Rupee.
Now ride the platform to the far side, and then continue in this direction until you find and defeat a Guardian Scout I. Use a bomb to blow up the wall behind it and continue onward.
When you reach the windmill, stand on the platform and use the leaf on the windmill, then glide to and open the chest, which contains a Forest Dweller's Sword.
From here, glide to the ladders and use a bomb to blow up the destructible floor at the top of the higher ladder. Ride this new updraft to the top.
The windmill up ahead makes another balloon-carried platform appear. Start by riding it to the chest on the right, which contains a Giant Ancient Core.
Now carefully ride the balloon platform past all the spikes to the next windmill. Stand on the platform and use the windmill to launch yourself up to the next area.
If you turn around, you'll see a large pillar of destructible blocks. You need to blow this up somehow. The fastest method is to use a Bomb Arrow to blowup the entire structure. If you don't have bomb arrows, you can use a nearby windmill to summon a balloon-carried explosive barrel. Using a Korok Leaf, Link can push this barrel over to the large structure and if the explosive hit the flame, it will explode, breaking all the boulders.
Hit the nearby windmill to launch yourself up and make your way to the updraft that was behind the destructible boulders. Ride this new updraft to the top for yet another chest, this time with a Small Key. Just down from here is a ladder with a small ledge pointing at your next destination. Glide over to this platform below the Sheikah symbol on the wall.
Use the Korok Leaf on the propeller. Ride the balloon platform to the chest with a Gold Rupee. Glide down to the chest with a Forest Dweller's Sword. Collect the chest with a Giant Ancient Core. Use a Bomb Arrow to explode the boulders. Open the chest for a Small Key. While falling down, don't forget the chest with a Thunderspear.