Mario first starts out on a long, flat platform. He must run forward, avoiding the Bob-omb in a bubble and jumping over two pipes. Between these two pipes, Mario finds a Dragon Coin and a Goomba in a bubble. After jumping over a bottomless pit, Mario has to avoid more enemies in bubbles and use the Jumping Board to jump over the tall pipe blocking his way. Between two pipes, there is a ? Block containing a green Yoshi Egg, which a Yoshi hatches from that Mario can ride. Then, after clearing the pipes, Mario finds a diagonal line of Rotating Blocks. Here, there are more bubbles, one containing a Super Mushroom and the rest containing more enemies. Next, Mario must jump across the bottomless pit and traverse the next platform. There is two Rotating Blocks stacked on top of each other; a Koopa Shell rests on the lower one, and another Jumping Board rests on the upper one. By hitting the lower block, the shell bounces up and hit the upper block, releasing a Jumping Board. Mario must grab this Jumping Board and jump on it to clear another tall pipe. A Dragon Coin can be found above a cluster of enemies in bubbles. After jumping across a bottomless pit, Mario finds four Goombas in bubbles and four randomly placed Rotating Blocks. Mario must avoid these enemies and run across the platform to find a Midway Gate.
After passing through the Midway Gate, Mario must dodge more bubbles, one of which contains a Super Mushroom, and jump over the bottomless pit. On the next platform, Mario finds two pipes next to each other, and a bottomless pit between them. A Dragon Coin can be found above the bottomless pit, and Mario can jump to obtain the coin. After these pipes, Mario must traverse across three more platforms, avoiding more bubbles and Rotating Blocks. Then, Mario must jump over the tall pipe blocking his way. The next platform has a plethora of erratically placed ? Blocks containing many coins, but also has a swarm of enemies in bubbles. A Dragon Coin can be found above these ? Blocks, which Mario must use as stepping stones to obtain the coin. Next, Mario must jump across a bottomless pit and dodge more enemies in bubbles. There is a Splittin' Chuck that Mario must dodge in addition to the bubbles. To get past this platform, Mario must use some Rotating Blocks as stepping stones to clear a tall pipe blocking the way. The last Dragon Coin of the level can be found on the ground next to the tall pipe. Afterwards, Mario finds a diagonal line of three ? Blocks, a small pipe, and, lastly, the Giant Gate.
Mario must progress through the level, up to the part with the Splittin' Chuck. Mario must jump up the Rotating Blocks and land on the tall pipe that he originally had to jump over. This pipe is actually a Warp Pipe, and takes Mario to a small, cave-like area. There is a key with a keyhole inside a cage of Rotating Blocks. As long as Mario is in his Super form, he can Spin Jump to break open the blocks. After breaking into the cage, Mario simply has to insert the key into the keyhole to access the secret exit. This alternate exit leads to #5 Roy's Castle, and is necessary to gain access to Chocolate Island and complete the game.