Current

Currents  appear in a few games as obstacles. While currents cannot hurt the player, they can push the player away or send them into a pit.

Super Mario Bros.
While currents do not physically appear in Super Mario Bros., the bottomless pits in all water areas in the game attempt to suck Mario down while he swims over them.

These currents also appear in Super Mario Bros.: The Lost Levels, again only in water levels and behaving exactly the same way.

Super Mario Bros. 3
Currents appear in Super Mario Bros. 3, now coming out of Warp Pipes and visibly showing a bubble jet. Again, they only appear in water levels, where they push Mario in the direction of the bubble jet. Frog Mario can fight the currents by pressing to do his fast swim; in World 4-4 and World 6-9, this can be exploited to find some hidden bonus areas.

New Super Mario Bros.
Currents appear in New Super Mario Bros., behaving the same as in Super Mario Bros. 3. Some levels feature currents that can be turned off if the player presses a ? Switch.

New Super Mario Bros. Wii
Currents return in New Super Mario Bros. Wii, behaving exactly the same as in previous games.

New Super Mario Bros. 2
Currents reappear in New Super Mario Bros. 2 behaving the same as in past games. In this game, currents are no longer limited to protruding from Warp Pipes, with some naturally occurring as well, as in Super Mario Bros. World 1-5's second Star Coin features a Super Mario Bros.-style downward current over a pit.

New Super Mario Bros. U / New Super Luigi U
Currents are featured again in New Super Mario Bros. U and New Super Luigi U, behaving identical to previous games. Like with New Super Mario Bros. 2, some currents occur naturally, such as the returning downwards currents featured in Tropical Refresher and Urchin Reef Romp.

Wario Land II
In Wario Land II, currents appear infrequently in levels such as Turn off the giant faucet! and Escape from the Tea Cup! They push Wario in the direction the water flows.

Wario Land 3
In Wario Land 3, currents appear in many levels, notably Bank of the Wild River, The Steep Canyon, and Beneath the Waves. One in the first of these must be clogged by the boss Pesce in order to continue.

Mario Kart 7
In Mario Kart 7, currents appear as obstacles that push racers around in Wario Shipyard and Piranha Plant Slide. In the case of the latter, one such current allows the player to access the Dash Panel over the last Piranha Plant before the Glide Ramp.

Mario Kart 8 / Mario Kart 8 Deluxe
Currents return in Mario Kart 8 and Mario Kart 8 Deluxe, behaving the same as in Mario Kart 7. They appear in Dolphin Shoals and 3DS Piranha Plant Slide.

Donkey Kong Country: Tropical Freeze
Currents also appear as obstacles in Donkey Kong Country: Tropical Freeze, where they are featured in some underwater levels. They are most prominently featured in Current Capers, where some currents in the level expand and contract. Dixie Kong is capable of fighting the currents with her hair spin.

Mario Party 10
Currents appear in Mario Party 10, in the minigame Blooper Blastoff. If interacted with, they push away the player's Blooper submarine.