Water

Water is a common, mostly harmless liquid that frequently serves as an obstacle and level theme in the Super Mario franchise. When entered, water can typically be navigated by swimming through it. It often appears colored light/dark blue or clear, and is seen many times throughout Mario and friends' adventures in the Mushroom Kingdom.

Water can contain a variety of enemies, some of the common ones being Cheep Cheeps, Bloopers, Urchins, and Cheep Chomps.

Super Mario Bros. / Super Mario Bros.: The Lost Levels
Water debuts in Super Mario Bros., first appearing in World 2-2. Enemies such as Bloobers and Cheep Cheeps are commonly found in the game's underwater levels. Smaller bodies of water that do not take up entire sections of levels also appear starting in World 3-1. This type of water cannot be swum in, and instead serves as a type of bottomless pit, causing the player to lose a life if Mario or Luigi falls in.

Small, non-interactable bodies of water reappear in Super Mario Bros.: The Lost Levels starting in World 1-2, though in the Super Mario All-Stars version, this type of water first appears in World 2-1 instead. Water that can be swum in and takes up entire sections of levels also reappears starting in World 3-2.

In the original Nintendo Entertainment System versions of these games, water uses the same graphics as lava, but colored blue instead of red. Small bodies of water are functionally identical to lava as well, since Mario and Luigi can fall through them and lose a life.

Super Mario Bros. 3
Water appears in many levels throughout Super Mario Bros. 3, first seen in World 1-5. Water can be found scattered in small pools in the ground, or taking up entire levels, and can be swum in in either case, as is the case for most games thereafter. In some cases, water contains enemies such as Boss Bass, Lava Lotus, and Jelectros.

Super Mario Land
In Super Mario Land, water is a staple element of the Muda Kingdom, as it is present in every level of the kingdom. Unlike in other Super Mario games, Mario cannot swim in water and will lose a life if he falls into it in an on-land level. Mario uses the Marine Pop to traverse levels that are submerged in water.

Super Mario World
In Super Mario World, water first appears in Yoshi's Island 4, taking up the bottom part of the screen. It appears in many later levels as well, either placing the whole level under water, or set in only in small sections.

Super Mario Land 2: 6 Golden Coins
In Super Mario Land 2: 6 Golden Coins, water first appears in Hippo, taking up much of the level, though the player is able to jump across platforms above it.

Super Mario 64 / Super Mario 64 DS
Water is a frequently recurring element in Super Mario 64 and Super Mario 64 DS, first appearing in the moat of the Mushroom Castle, and many times in some of the levels themselves, such as Jolly Roger Bay, the Hazy Maze Cave, and Wet-Dry World. When Mario becomes Metal Mario, he is able to walk under the water as he would on dry land.

Super Mario Sunshine
Water is a central game mechanic, as well as an obstacle and world element in Super Mario Sunshine. Mario can spray water using FLUDD, which is necessary to interact with many objects and enemies in the game, most notably to clean up goop. Splashes of water like those produced by FLUDD can also be produced by breaking Water Barrels, dripping off of Mario for a short time after he exits a body of water, and by Yoshis briefly before disappearing if they run out of juice. These splashes of water annoy Piantas and most other friendly characters if they come into contact with them, causing them to become angry at Mario.

FLUDD has a limited water tank, which can be refilled in bodies of water or by picking up Water Bottles and coming into contact with water fountains found in some areas. Bodies of water appear in almost every level, particularly in the ocean around the edges of Isle Delfino. If Mario enters water deep enough to swim in while riding a Yoshi, or dismounts a Yoshi in shallow water, the Yoshi will disappear.

New Super Mario Bros.
Water appears most commonly in New Super Mario Bros. in World 3, which mainly consists of beach-themed levels that contain water. However, water also appears in some levels outside World 3 as a key component.

Super Mario World 2: Yoshi's Island
Bodies of water appear in many levels in Super Mario World 2: Yoshi's Island, starting in Touch Fuzzy, Get Dizzy. Yoshi automatically rises to the surface and can therefore can only swim near the surface of water in this game, although he may dive slightly deeper by jumping into water from a high place, which can be used to get under certain barriers. Deeper water can only be traversed as Submarine Yoshi.

Eggs can be skipped along the surface of water, including after ricocheting off of walls, which is necessary to collect certain items as well as to damage Naval Piranha.

Various enemies are found on the surface of water, such as Spray Fish and Nep-Enuts, and in deep water, such as Loch Nestors and Preying Mantas. Cheep Cheeps appear both on the surface of water and underwater, known in English as Flopsy Fish when on the water's surface and Piscatory Petes when underwater.

Paper Mario
In Paper Mario, water cannot be entered or even jumped over unless Mario is riding Sushie, who allows him to swim over the surface and briefly dive beneath the surface. Mario can only start riding Sushie while standing on wooden docks, so not all bodies of water can be traversed this way.

Sushie's Squirt and Tidal Wave moves involve her using water to attack enemies and have a water-elemental property, which allows them to deal additional damage to fiery enemies such as Lava Bubbles. Similarly, Sushie's Water Block move provides additional protection to Mario against fire-based attacks due to its water-based nature.

Paper Mario: The Thousand-Year Door
In Paper Mario: The Thousand-Year Door, Mario can safely jump over water. However, if he lands in water, he is invariably attacked by Nibbles, damaging him and forcing him back onto land, unless he is in Boat Mode. Boat Mode can only be activated while Mario is standing on special boat panels, similarly to Sushie's wooden docks, so much like in Paper Mario not all bodies of water can be safely traversed.