This level is a bit different then others you’ve played in as Key Coins are introduced. They are a collectible that you must obtain in order to unlock the Warp Box and reach the next area. From the start, head onto the dock in the background for Key Coin #1 but Biddybuds will fight you for it. Continue right into the small pit to find a Boomerang Flower which comes in handy. Break the Goomba sand statue here to find Green Star #1 then enter the T-Shaped Clear pipe, emerging at the top.
Grab Key Coin #2 here then head out towards the water. The sand rises but the water stays at sea-level, obviously. With that knowledge, run under the sand towards the screen to find Key Coin #3 . Cross the water right and you can find a 1-Up Mushroom and Boomerang Flower by using the pipes. On the island between the pipes, climb atop the palm tree for Key Coin #4 then go right to the Chargin’ Chucks. Defeat them with a Boomerang toss and snag Key Coin #5 . Going out of order, continue right up the ledge into a hidden room with Green +Clocks and Green Star #3 .
Head towards the Warp Box in the water now but continue left of it to find a pipe submerged in water. In the bonus room you’ll need to light the floor panels to spawn Green Star #2 .
Take the Warp Box to the Checkpoint Flag and use the pipe here to catch a ride of Plessie. Stick to the right side and make a leap over the docks to the Stamp on your way to the Goal Pole.