Starting where you picked up the first Resonance Orb, head up and to the left. Hit the red lever to open the gate.
Continue up and hit the next lever to open the gate to the Tyne Wellspring.
Head right and relive your moment of glory against The Watcher.
Continue right, up and over the green clam and continue right.
Grab the green starfish and head back to the clam.
Feed the starfish to it, and you'll get a gold treasure.
Keep heading right to the Tyne Wellspring and crab. While you're here, why not pick up the Tail Cooler for 600 coins (and whatever else you can afford).
Head down and take the passage to the right to travel, once again, to Merrow Ruins.
With the freshly upgraded boost, it's easier to finally get that treasure in the top right corner. Head right, just past the clockwork cannon. To the right and just below it is a bomb. Grab the bomb and head up and right. Boost toss the bomb to blow up the gate and claim your prize of 10 coins.
Backtrack to the Tyne Wellspring and head down, through the lantern jellies again.
Head straight down to the bottom, passing to the left of the clam this time to find a hidden area with a few coins inside.
Head back up and go all the way to the left. Make your way down past the Tyne Vortex again and take the right at the crab.
Pass through Cara's chamber and keep heading right.
Keep going right, past the Tyne Wellspring and statues in the next room. Take the tunnel out to the right from there and exit the next room at the bottom right.
Turn up until you see a wooden wall you can break through.
Make your way past the pistoning pillars in small steps.
Continue right to the pair of wooden walls and then on to the closed gate.
There's a statue on the other side of this gate that has a head, but this one is missing its torso. Exit the sub as Merryn and then head up.
Go up as far as you can until you see another disassembled statue. You can pick up the torso here and return with it to the sub. Swap out the torso and the head and put them in the right order to open the gate.
Take the sub all the way back up to where you picked up the torso, blow up the wall and take the path right.
There are a couple more statues to reassemble here. Go to the bottom and exit the sub. Use Merryn to head to the left and up to retrieve a head.
Carry it up through the small tunnel and install it on the statue on the left to open the gate.
Bring the sub up and use it to pull the handle to open the gate on the right.
Quickly drag the statue's tail through the gate and straight down to install it on its base. Then head left to grab the statue's torso and drag it back.
Send Merryn out on her own again to pull the head off of the first statue and bring it back.
Take the sub through the gate that opens to the next Tyne Wellspring.
Boost your way past the first set of pillars, then take the bottom path. There's a treasure up top, but our current boost abilities make it very difficult to get.
Keep heading right to the next Tyne Wellspring and then continue on into the large room that totally feels like it should be where you pick up the Resonance Orb, but isn't.
Blow up the gate at the top of the screen to let the light shine in, which activate the switch at the bottom.
Send Merryn down and to the left.
Stick to the blind spots of the cyclops as you enter.
There's a hiding spot right above you that's out of the current and out of view of the cyclops.
When the cyclops looks to the right, duck down, rush left and grab the treasure at the bottom. You can wait out the cyclops' next cycle here. Head back up and into the tunnel on the left to (finally) go get the second Resonance Orb.
When you make your way back to the sub, use the current for a quick way past the Cyclops on your way out.