You have 100 seconds to finish this level and all the Fire Bros. and Goomba Towers in the water must be defeated to spawn the Warp Box out. Start by dashing to the far left and grabbing a Fire Flower enroute to Green Star #1 .
Light all the torches and defeat the Goomba Tower then grab a nearby Cannon Box and rush to the far right side. Blast the Goomba Tower here and collect Green Star #3 then move back to center. Jump in the clear pipe to reach Green Star #2 then move to the Goomba Towers, firing cannonballs to quickly dispatch them. Don’t waste any time, just progress to the Goal Pole.