This course moves away from the norm we are used to seeing in this game. The koopa troopas have command over this level and can easily kill you if you don't have split second timing. This is the only part of the game where you're going to see ice blocks, light blue pipes and fancy little platforms. Watch out for the flying fishes we seen in Super Mario Brothers back in the 80s
Several shell-less Koopa Troopas await with a shell atop U-shaped chasms. If you run to the right side of the chasm and wait, the shell the Koopa throws won't return. When you arrive at a pit with P-Switch on a corner, don't activate the switch. Carry it with you until you see a coin platform and a [?] block. The block contains a star, which will help a lot during the next stage.