- "In the World 1 Castle, Mario uses his Wall Jump technique to reach an elusive Star Coin."
- ― New Super Mario Bros. official website
In the first part of the level, there is a tightrope and a Podoboo. Then, there is another tightrope and a Question Block on top of a rising platform. Mario will then have to jump over a pit to the next platform to proceed. In the gaps between the next few platforms, there are Podoboos, so Mario must be careful in this area. After this, there is a longer gap without a Podoboo and a Dry Bones. After this Dry Bones, there are walls with spikes on them, and Mario can be crushed by them. Between two of the walls, there is a Question Block, and in another gap, there is a block which Mario can repeatedly hit to get many coins. If Mario Wall Jumps in one of the gaps, he can get the first Star Coin of the level. After that, Mario will come across another tightrope, and he will get to the Midway Point of the level. After this, there is another platform and a few more tightropes, as well as another Podoboo. After the tightropes, there is a Dry Bones on top of a platform. The platform beside the platform with the Dry Bones will rise in and out of the lava, and if Mario jumps on top of it quickly, he can grab the second Star Coin in the level. Then Mario should jump over another Podoboo, and he will encounter two more platforms, one of which has a Dry Bones on it. Mario should avoid the Podoboo, and then enter the battle with Bowser. Before battling the Koopa King, Mario will walk through a hall filled with statues of Bowser. Then, he will enter a room similar to Bowser's room from Super Mario Bros. In the fight with Bowser, Bowser will attack by shooting fireballs at Mario. Mario can easily defeat him by jumping over Bowser with the platform in the room and hitting the switch, which will destroy the room's floor. Hitting Bowser nine times with fireballs will finish him off. When Bowser falls into the lava, he will transform into Dry Bowser, and World 1 is completed.
- Star Coin 1: In the middle of the crushing stone section, wall jump to reach it.
- Star Coin 2: Above a small stone platform that sinks in the lava, when it rises out jump and get the Star Coin before it sinks back in and kills you.
- Star Coin 3: In a hidden pipe above a long tightrope close to the boss door above some coins. Jump high into the air, enter the pipe, and the final Star Coin will be in a small room.