World 8 is the eighth world of Super Mario Bros. This is the final world in the game, leaving only four levels left in the game. In World 8, three ground levels are traversed, as well as the final castle level, which has an underwater section. World 8 is the only world in Super Mario Bros. without any checkpoints; the player is sent to the start of the level if defeated.
 Level Information
||In this level, the first enemy encountered is a Buzzy Beetle, followed by a chain of other enemies. A pipe with a plant inside is encountered. A series of large gaps and Koopas are then encountered throughout the level adding additional challenges. Certain large gaps have a mere single brick within it to land on, requiring good timing to make the jump. This level is rather long while the time limit is comparatively meager. Despite the constant presence of one brick wide platforms, the player can easily pass many of them by running and jumping over them. Once the flagpole is touched, the level ends as always.
||The first thing encountered in this level is a staircase followed by a pair of Koopa Paratroopas, a Lakitu, and a rainstorm of eggs. Another pair of Koopa Paratroopas are encountered beneath a long stretch of brick blocks (in which an extra life is hidden). Over more gaps and pipes, and through mazes of Bullet Bills, the player once again reaches the levels end.
||This level features a wide array of enemies, from Piranha Plants to Hammer Bros. to Bullet Bills. The player must lunge over pipes, run around bullets, and try to avoid oncoming hammers in order to survive. This level is the first of only two levels to feature Hammer Bros separate from each other. Once a shattered ending staircase is encountered, the final flagpole is seen for the final time in the game. Only one level awaits: Bowser's Castle.
||This is the final level of the game, and features mass amounts of high difficulty. The player must solve puzzles and enter pipes in certain orders to continue to the next section. Almost all enemies are encountered in this level, and also an underwater area must be successfully completed in order to move on. The real Bowser is finally encountered in this level in a no-holds-barred final battle against the player. Once Bowser is defeated, Princess Toadstool is finally rescued, and the end of the game is reached. The princess thanks the player and adds an additional challenge to the game: Buzzy Beetles in place of all Goombas and faster-moving enemies.
 Levelmaps (All-Stars version)
- A minor change to the soundtrack occurred between the original NES version and the All Stars version. In the NES version, when undergoing the underwater portion of the game, the music playing in the background was the underwater theme for most areas. In the All Stars version, it was the castle theme.