Coin #1 1/4 of the way through the level, hit the ? block and grab the mini mushroom. Go back a few steps to see a tiny pipe; go down that. The coin is on the right side of this area. Coin 2: A bit more than halfway through the level, there is a large walled-in area with a red turtle before it. Step on the turtle, then grab it by holding the B button; throw its shell into the walled off area, then when it finished bouncing around, go down the pipe. Do not collect the coins; instead, hit the last block before the up pipe, then hit the P switch. Jump up the blocks and collect the coin. Coin 3: A bit more than 3/4 of the way through the level, the coin can be seen under an overhang. As little Mario, hold B and dash across the hole in the ground, then grab the coin.