Snow World
The Snow World is a large, windy, and frigid area that is quite desolate and bleak. It only appears in The Super Mario Bros. Super Show! episode "Brooklyn Bound".
Aside from a few stone protrusions poking out of the snow, there is nothing noteworthy in the Snow World. The wind is extremely powerful though, as it has been shown to, on one occasion, blow Mario, Luigi, Princess Toadstool, and Toad through the air.
Underneath the Snow World is a large series of caverns and a river of lava. A large drainpipe that can transport someone to Flatbush, Brooklyn is also located in the caverns, though this drainpipe later becomes unusable after the legendary plumber, Salvador Drainotto, uses it. Salvador Drainotto installs a large piping system in the tunnels beneath the Snow World.