SleepingSwamp

The Sleeping Swamp has both options to upgrade your hearts by talking to the light blue fairy to the south of the entrance. There's also a Puzzle to the north that has to deal with walking on the backs of turtles.

Puzzles
To complete the puzzle you need to walk across the back of the first two turtles who will move, once you move to a certain spot your fairy will start singing a modem noise, which you need to disable by lowering the level of the sound so the turtles won't drop under water forcing you to restart the map.