Knot-Wing the Koopa's Aqua Fort

Knot-Wing the Koopa's Aqua Fort is the fourth level of World 4 in Yoshi's Woolly World.

Layout
The level starts in an area with Poochy, followed by a pipe that Yoshi can enter. It leads to a sewer-esque area with Koopa Paratroopas and Cheep Cheeps. By hitting a button, Yoshi can lower the water level, and swim through the flipper to an area with swimming Ukikis, where he can raise the water level again. This leads to another warp pipe, where Yoshi can find a hidden Winged Cloud which will reveal a staircase when hit. When taking the staircase, Yoshi must hit another button to lower the water level once more. Once the lower level is reached, Yoshi must raise the water level once more and sidle to the left, hit a Winged Cloud to unveil a platform that leads directly to a door, then hit the previous button to lower the water level again and enter the door. The first checkpoint immediately follows, which encompasses a near-symmetrical room. Yoshi must hit a Winged Cloud at the bottom right of the room, then hit the button to raise the water level again. Yoshi will reunite with Poochy, and must lower the water level to get Poochy down to the desired level. Yoshi must then raise the water level again to make his way to the top right with Poochy, then press the nearby button to lower the water level again. He must then eat an edible wall at the bottom left of that room, then hit a previous water level altering button via yarn ball to raise the water level again. He must then guide Poochy to the right to grab the key, then to the left to unlock the Locked Door, which leads to the second checkpoint. The final stretch is an obstacle course consisting of many spikes to avoid. Yoshi must simply hit the button at the top to lower the water level, swim back down, and enter the boss door.

Smiley Flowers
lowering the water level. Yoshi must then ground pound when he gets close to the Smiley Flower before the Koopa Shell hits the button the raise the water level again.
 * Smiley Flower 1: When raising the water level via the button next to the first two Ukikis, Yoshi can travel through a hidden alcove on the left to collect the Smiley Flower.
 * Smiley Flower 2: When lowering the water level in the second area, there is a wall to the right with an edible wall and a Koopa Shell Patch. Traveling through the alcove will take the player to the Smiley Flower.
 * Smiley Flower 3: While utilizing Poochy in the room with the first checkpoint, Yoshi must lure him to the top left corner of the room, and allow him to jump so that he can enter a hidden alcove with a door. Inside the secret room, Yoshi must kick a Koopa Shell into a button,
 * Smiley Flower 4: In the room with the key, unveiled after hitting a hidden Winged Cloud next to two Clawdaddies.
 * Smiley Flower 5: In the room with the key, in a hidden alcove underneath the platform with the two Clawdaddies.

Wonder Wools

 * Wonder Wool 1: Rather than taking the normal pipe near the start of the level, Yoshi can use Poochy to jump into a hidden alcove on a right wall. Taking the warp pipe in this area leads Yoshi directly to the Wonder Wool.
 * Wonder Wool 2: On top of the exit point of the second warp pipe, Yoshi must push the wall back to reveal the Wonder Wool.
 * Wonder Wool 3: In an alcove just by the first checkpoint. To get it, Yoshi must lure Poochy to the area, then allow him to grab the Wonder Wool.
 * Wonder Wool 4: When reaching the bottom right corner of the room with the first checkpoint, Yoshi must allow Poochy to jump up so that he can eat an edible wall with a Koopa Shell Patch and grab the Wonder Wool.
 * Wonder Wool 5: After hitting the final button, Yoshi must touch the now-uncovered exclamation circle and quickly follow the beads to the Wonder Wool.

Collecting all of the Wonder Wools knits Aqua Yoshi back together.

Enemies

 * Koopa Paratroopas
 * Cheep Cheeps
 * Ukikis
 * Koopa Troopas
 * Koopa Shell Patches
 * Clawdaddies
 * Hook Guys