Take the yellow pipe at Point 2 to find a small room with a Porcupuffer and two ? Blocks.
Get the power-ups in the ? Blocks and then exit. If you have the Fire Flower power-up, you can blast the Porcupuffer and get three 1-Up Mushrooms!
New Super Mario Bros Wii eGuide Walkthrough World 4-Water World
World 4-4