Behind the red-blue metal chunk, found soon after jumping into the water.
Found after jumping onto the high treetop from the swinging platform and pounding next to the Plump Yellow Fruit
After opening the two platforms, the player must grab the flying banana which will turn into a puzzle piece.
In an area revealed by pounding right under the first Chomp in the metal-like area.
After getting Diddy Kong, the player can go back and jump on top of the previously mentioned Chomp and get the piece which is on a platform above it.
Spinning in the air, the player must time their shot from a Barrel Cannon correctly to get it.
Upon pounding on the crate after the second platform in the beach area with the pirate ship, there will be a secret underground area where some Tutorial Pigs will give the DK and Diddy bananas, and a puzzle piece afterwards.
Shooting through the barrel above the swinging platforms will reveal a secret area containing a large amount of bananas to collect in 30 seconds, after which the Kongs will get the Puzzle Piece.
The final Puzzle Piece is obtained by going to past the end barrel and pulling the plug which will reveal it.