Submarine

A submarine is a real-life underwater vehicle used in the Mushroom Kingdom.

Super Mario Land
In the Muda Kingdom area, Mario can use his submarine, the Marine Pop.

New Super Mario Bros. U
The course, The Mighty Cannonship's boss uses Bowser Jr. using his Koopa Clown Car for an underwater battle, adding a air tank, which gives it a submarine-style machine.

New Super Luigi U
The Koopa Clown Car's air tank is used again in All Aboard!, with Bowser Jr. as the boss again in New Super Luigi U.

Mario Kart 8
Submarines are seen in Mario Kart 8. They appear in the course Water Park, where they are controlled by Nokis. Also a stamp can be unlocked in the game.