Super Mario Bros.: World 6-2

You can go down the first pipe for coins underground or continue ahead. After 2 garbage blocks, one pipe leads to an underwater course where you'll find more coins. If you hit an invisible block by one pipe, hit the garbage block above it to reveal a vine and go to the sky for coins. After revealing a Star from a garbage block, a pipe between 2 hard walls leads to another underground course where even more coins are found. Pass a few more pipes and you'll see Paratroopas incoming on the stairway. Cross the stairway and you'll reach the flagpole.