In a clear tube after the second Bell block. Climb on top of the tube to get it or hold UP while in the tube.You can also climb the the clifftop and then drop down to get it. Use the Cat Suit to climb ...

Don't leave the first underwater area via clear pipe. Travel up above it and the water will raise to allow you to grab this Green Star. Get the Cannon Box near the Stamp and sink down to the bottom of ...