The level starts with Mario outside in a volcanic environment. Reaching a crater, Mario and Kersti jump down inside, landing in the volcano's interior. Just as Kersti is remarking about how amazed she is, Petey Piranha flies up and eats her; as such, Mario cannot paperize or use the Battle Spin for the remainder of the level. Additionally, by peeling off some nearby Bowser Tape on a bridge, the bridge does not gain another segment to complete it; instead, the entire platform Mario is on is sent deeper into the volcano.
Not too far away is a platform, which at first seems to send Mario to Petey Piranha, but instead rockets him further up. Here, he can see several stickers, Spear Guys and a Big Chain Chomp suspended from chains above. By heading into the nearby room, the Big Chain Chomp from Chomp Ruins emerges from the lava, chasing Mario out of the room; in the other room, it eventually hops onto the platform, embedding itself into it, which both knocks it out and lowers the platform.
On the next lowest section, there is a sticker shop in the nearby room. Right near the shop is a Warp Pipe, which takes the player to a platform next to the one Petey Piranha is on; however, if the Mario goes here too early, he is blocked by the geyser of lava suspending the platform above. In the room after the sticker shop, Mario encounters a Big Chain Chomp, which immediately forces him into battle. Mario must put it to sleep, flee and hammer the stake, then wake it back up; the Chomp lunges at Mario, which sends it out of the battle, off the nearby ledge, and into the platform below. This allows Mario to access the next section underneath it.
In the next section below, there are eight stakes, each one with chains attached to it. By hammering the stakes, it sends down either one of the stickers or one of the Spear Guys at the top of the screen; each of the chains hammered corresponds to the object suspended from that chain (i.e. hammering the chain on the far left causes the object on the far left to fall). By hammering the stake with the Big Chain Chomp, however, nothing happens; by going into the next room, it can be seen that a piece of Bowser Tape is keeping the Chomp from falling. In this room, the player must navigate using several platforms that rise and fall with lava geysers to access the platform with the tape, and peeling it causes the Chomp to fall onto the platform below (assuming the stake has already been hammered).
Climbing on the platform lowers the player to Petey Piranha's platform. Immediately after climbing off, there is an HP-Up Heart nearby. During the battle, Petey, once damaged enough, spits out several Jump Stickers, Dry Bones, and eventually Kersti. After Petey Piranha is defeated, Mario can obtain the fifth Royal Sticker.
By returning here after defeating Petey, the entrance has been boarded up; instead, a Warp Pipe grants access to the interior. The bridge leading to the platform has also been repaired, and the platform with the three Chomps embedded in it lowers when Mario steps on it; if it is at the lowest point, it shoots back up to the top.
After Defeating Petey
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