New Super Mario Bros.: 3-A

The path forks after 3-1, so we'll be going here first. There are water striders throughout the level that periodically drop bombs and barrels bobbing in the water. The Red Coin Ring will make Red Coins appear over the land and under water, so you'll have to be quick to get them. There are carousels in the water. Stand on the side of the direction you want to go. We have to go under a ledge and let a strider bomb the rocks surrounding the first Star Coin. The midpoint is soon after that. There are more barrels, so we double or triple jump off some barrels to reach the second Star Coin. The end of the first part of the level is marked with a pipe. There's another carousel in this part, as well as a mini pipe, which is not necessary to reach the last Star Coin. We go up a pipe to the area with the third Star Coin. We need to be Mini Mario to reach it by running across the top of the water, then wall jumping to reach it. We return to the main level and soon take the pipe to the flagpole.