Vanilla Fortress is a fortress in Vanilla Dome, which is located in the water (as seen on the map), as the entire fortress is flooded inside. By completing the fortress, the player will gain access to the Twin Bridges, and unlocking Butter Bridge 1.
Note: The Dragon Coins can only be found in Super Mario Advance 2 version.
The player enters the room from a pipe, and will encounter a Ball 'n' Chain along with a Fish Bone. Another Ball 'n' Chain will be encountered, and after that one, a small path with spikes above can be seen, however can only be entered as small Mario. Avoiding the Fish Bone, the player can enter the Warp Pipe to take them to the second room. However, the player can still go upwards the regular way, swimming past a pit of spikes after another Ball 'n' Chain and eventually to a ? Block. After passing the block, the player will reach an area with a ceiling of spikes, with a couple of Falling Spikes that the player should avoid. In this area is a few skeletal enemies, such as Bony Beetles and Dry Bones, as well as the first Dragon Coin. After that is a purple pipe that warps to another pipe in the room.
If the player took the green pipe, they will find the second (or first, depending on how the player collects them) Dragon Coin on their left. Going right, they will encounter two Fish Bones as they move ahead, and a Thwomp. By swimming upwards the player will find the checkpoint (only on the GBA version), and by avoiding the Ball 'n' Chains swinging by, the third Dragon Coin will be found. Swimming left is the fourth Dragon Coin, right by a Thwomp, and by swimming more to the left, is the fifth Dragon Coin also in the path of a Thwomp. The player should make their way back to the right and avoid the Ball 'n' Chains, and just below a more higher ground is an extra sixth Dragon Coin, that the player can grab or not grab as it's optional.