World 3-3 (Super Mario Bros.: The Lost Levels)
From the Super Mario Wiki, the Mario encyclopedia
World 3-3 is the third level of World 3 in Super Mario Bros.: The Lost Levels, taking place in the heights. In the original and Super Mario Bros. Deluxe releases, this level is snow themed, though it uses grassland tiles in Super Mario All-Stars. It is worth noting, however, that no snow-themed tiles for the tall tree-like platforms exist in the latter.
The player begins facing a high platform they need to jump onto before coming to a row of Koopa Troopas and a Koopa Paratroopa on the next couple of platforms. After the first pipe with a Piranha Plant is a scale lift that leads into a couple more platforms with additional Piranha Plants in pipe, after the third of which is a Super Spring. Over the next tall platform is a Hidden Block containing a power-up, after which is another scale lift. Beyond the Koopa Paratroopa afterward a platforms that start to fall when the player lands on them with a pipe with a Piranha Plant between them. Afterward is a platform with Hidden Blocks above it that can be used as a platform to make jumping across the next segment easier. After the next Koopa Paratroopa is the Goal Pole.