Star Coin 1: To the top-left of the second swinging platform (the one with the ? Block), the first Star Coin floats in a small opening in the rocks, to the left of many Coins. Mario and co. must jump up from the swinging platform to get it.
Star Coin 2: On top of the three swinging platforms, go to the right and wall jump to the top.
Star Coin 3: Above the Roulette Block is another split path. Mario and co. must use the lowest swinging platform to jump up to the second swinging platform, following the path on the right. Then, when the swinging platform swings to the left, jump up to the third Star Coin which is high up to the left.