Cara marks three locations on your map where you'll find Resonance Orbs. Head to the one in Watcher's Hollow first. Head through the gate to the left of the wellspring.
Retrace your steps to the left until you see a gold treasure below you. Use Merryn to retrieve it.
From there head up and left and torpedo your way into a new area of Watcher's Hollow. This isn't the most direct path to the orb, but you're going to pick up an upgrade that you'll need on the way.
You'll see a new type of gate that you can't open yet. Collect the coins and keep heading up.
Pause to blind the eyes with your searchlight to get a gold treasure, then continue up.
Use the wellspring, then break into the path directly above you.
You'll encounter new type of Formori device that tries to shove you into the stinging nettles. Just take your time and use the convenient anchors to protect yourself.
Keep doing that all the way around to the right and down.
Break through the wall, and pull the handle at the very bottom (you're protected from the shock waves here, by the way).
Pass through the gate that opens to a new wellspring.
Smash the pottery for a few coins as you head left to pull the handle. Head through the gate to pick up the Magma Bomb.
The Magma Bomb will let you break through those new ice gates you've encountered here. Start using them now.
Head back down to the right to the first one you saw on your way in.
Head up for a chest containing a gold treasure worth 75 coins, and then make your way down to collect a few more coins on your way to the exit.
Head back up to the wellspring and continue left. Open the ice wall directly in front of you and destroy the two windmilling squid that spawn.
There's a secret passage through the wall on the left that leads down to a green gem worth 100 coins.
Blast your way out to the main path, then head down.
Blow up the regular rock gate blocking your path.
Knock down the dangling rock to break a chest containing another Hull Fragment.
Blow up the gate above you get access to a silver treasure worth 75 coins.
You've also opened a shortcut back to areas of Watcher's Hollow you've been to before, but we're interested in heading a new way. Backtrack and head up until you see a wellspring.
Save and then magma bomb your way to the left.
Take out the windmill squid first, then follow one of the cuddlepups as it makes its way up and around through the anemones, then duck into the hollow. You've seen this puzzle before. Grab the handle to open the gate on the right of the screen, then hop out of the sub as Merryn. The sub will keep the gate open for you while you work your way around.
Follow the cuddlepups around, and grab the statue's head. Carry it up and to the right to install it.
Return to your sub, and head up and through the gate you just opened.
There's a secret passage to the upper left. Go through it, defeat the enemies and turn right.
Use Merryn to retrieve the statue head down the narrow passageway.
Carry this up and to the right to open a gate protecting another statue head. This will make sense in a minute.
Pick up the head you just freed, backtrack to the narrow passage, then continue right. You'll see two headless statues. Deposit the first head and go back to the one you used to open the gate protecting this one.
Yank it free and bring it back.
Installing the second head opens the gate on the right where you'll find the first of the Resonance Orbs.