50m

50m is the second level of the Donkey Kong arcade game and Donkey Kong for the Game Boy. This level has a series of conveyor belts which run along the second, third and fourth floors. This level has hammers to smash Fires and Sand Piles. There are also ladders, which Mario must climb. The top ladders will also disconnect and connect when Donkey Kong beats his chest, which he does instead of throwing barrels like in the first stage. The Oil Drum in this level is in the middle of the stage, and will produce more Fire to burn Mario. Lastly, because the top floor is a conveyor belt, Donkey Kong will be moving left to right throughout the level. As Mario reaches the top, Donkey Kong will take Pauline again and will climb up to 75m. In the Game Boy version, this is the location of Pauline's Parasol.

Trivia

 * This is also the only level where Donkey Kong moves, though technically it is the conveyor belts which are moving.
 * This level was removed from NES version due to a memory limit.
 * A newer port of the NES version (named Donkey Kong Original Edition) includes this level pre-installed for the European release of the Mario 25th Anniversary Wii. Unlike the arcade version, Donkey Kong stays noticeably still.
 * This is the only level in which Donkey Kong's action doesn't make something appear (25m makes barrels, 75m makes Springboards, and 100m makes Fire).
 * The original music for this level in the Arcade version is replaced by 100m's music instead.