Goop

"As you are no doubt aware, someone has been senselessly defacing fair Isle Delfino using some paint-like substance. The accused is charged with polluting our beautiful home and yes, endangering our very way of life. Indeed, how can one not be aware of what is going on? Though it is daytime in Delfino Plaza, our poor residents tremble beneath a veil of darkness. Expert Shine scholars have determined that this darkness has arisen because all of our guardians, the Shine Sprites, have vanished from their gathering spot at the Shine Gate. The reason? It's quite obvious. This horrible graffiti is to blame!"

- Pianta prosecutor

Goop, also known as graffiti, is a thick, slimy, paint-like residue that Mario is forced to clean up with the help of FLUDD in Super Mario Sunshine. Goop typically has adverse effects, such as being able to sink characters, trees, or structures through the ground, but can also be used as a means of transportation across Isle Delfino. Bowser Jr. creates most of the goop by using his Magic Paintbrush while under the guise of Shadow Mario.

A number of enemies can be encountered through goop. Gatekeepers appear from mounds of goop known as Generators, while Swoopin' Stus can emerge from areas covered by it.

Goop
The most common variant of goop is a tar-like substance used to slicken the ground and cause Mario to lose traction. If Mario stands on goop for too long, he will sustain damage every few seconds (the amount of damage sustained depends on the type of goop). It also dirties and sticks to his clothes, which can be cleaned by spin-jumping or swimming in clean water. This variety is found almost everywhere. Some enemies release it, while others are infused with it. It is found in many colors, and it is easily confusable with burning goop and electric goop. Generators are sometimes paired with common goop. According to a certain Pianta in Delfino Plaza who got stuck in it, it tastes "sweet," and he likens it to "candy."

There are three different types of goop:
 * Goop that is pink, yellow, orange, and white, which appears in the Delfino Airstrip and Noki Bay
 * Brown-and-white goop, which appears in Delfino Plaza and Bianco Hills. Petey Piranha launches this type of goop from his mouth.
 * Black goop, which appears in Delfino Plaza, Ricco Harbor, and Noki Bay when released by Bloopers and Gooper Blooper

Graffiti
Graffiti is the main type that Shadow Mario uses throughout the game. It is usually painted on walls, though it also appears on other flat surfaces. The Magic Paintbrush has a seemingly endless supply of it, and it can be used to create other types of goop. For example, Shadow Mario is seen painting Rainbow Ms with the Magic Paintbrush, which is tipped with graffiti. There is also a "raw" form that Shadow Mario uses to paint his infamous "M" signature, known as M Graffiti, which also appears as a logo at the beginning of the game. Along with Shadow Mario's signature, there are also painted symbols that come in pairs, known as Paired Graffiti. The symbols that appear are "×" (X Graffiti), "○" (O Graffiti), and "△" (Triangle Graffiti). Graffiti is most often colored red, though green graffiti appears in Ricco Harbor, and black graffiti was used to deface the Shine Monument, as well as the bells inside Delfino Plaza's two bell-towers. When graffiti is sprayed long enough, it will be completely cleaned off the wall. After it is cleaned off, a Blue Coin will be released for Mario to collect (with the only two exceptions being the two graffiti "M" symbols on the sides of the water tanks at the Delfino Airstrip, which release only regular gold coins). In the case of paired symbols, when one symbol is cleaned off, the Blue Coin appears next to its matching symbol, and vice versa. If Mario does not collect the Blue Coin in time, it will disappear, and the graffiti he cleaned off will reappear. He must then backtrack and clean it off a second time to make the Blue Coin appear once again. Mario will earn a Shine Sprite for cleaning the graffiti off the Shine Monument and each of the two bells.

There is also ink goop on the wall near the crates where Gooper Blooper is fought for the first time in Ricco Harbor. It cannot be washed off, but it does not hurt Mario. The goop leaks out of the crates Gooper Blooper is in and runs down the wall into the water, making it a type of slimy water.

Another type of graffiti appears during Episode 1 of Noki Bay. This graffiti is pink, yellow, orange, and white, and several blotches of it are positioned at intervals along a tall cliff face near the starting point of the level. These goop blotches are shaped like various things relating to the sea, including a squid, a sailboat, a dolphin, a whale, an octopus, and a bird. This graffiti can be cleaned off by Mario, but it cannot hurt him. As Mario cleans the blotches off, platforms of varying sizes appear out of the cliff face, which he can then use to climb upward. Cleaning off all of this graffiti helps Mario reach the cork plugging the waterfall, where he has to defeat a Monty Mole in order to finish the episode.

Rainbow M
A Rainbow M or "M" Teleport is a multicolored M Graffiti used to teleport Mario or Shadow Mario to other parts of Isle Delfino, serving as a subset of the Level Gate. There are three of them, all of which are found only in Delfino Plaza. The first was painted by Shadow Mario to escape Mario after he foiled the former's first attempt to kidnap Princess Peach in Delfino Plaza. This one was painted on the base of the Grand Pianta Statue, and it leads to Bianco Hills. Two more Rainbow Ms can be found on the side of the boathouse (leading to Ricco Harbor) and on the front of the lighthouse (leading to Gelato Beach). These Rainbow Ms appear only after the Gatekeepers covering the buildings have been defeated. All Mario has to do is squirt water on a Rainbow M to activate it (after which it becomes a portal to its corresponding location) and then jump into it. The goop that comprises the Rainbow Ms is also found inside two red Warp Pipes: one on top of a building located behind the Grand Pianta Statue (where it is plugged up by a large pineapple at the start of the game), and one on top of the Shine Gate. These Warp Pipes provide access to Sirena Beach and Pianta Village, respectively. Pinna Park and Noki Bay are the only levels that are not accessed via Rainbow Ms. When Mario uses one of the three Rainbow Ms, he is fragmented into multiple particles before entering, after which he is reassembled at the start of the level (similar to what happens when Luigi is transported through the Pixelator in Luigi's Mansion: Dark Moon or a playable character uses Candy in Mario Party 8).

Orange Juice Generator
Orange Juice Generators, also called Juice Generators or OJ Generators, are wavy force fields that block access to items, prevent Warp Pipes from being entered, and damage Mario on contact. These shields can be dissolved only by juice spat from a Yoshi. They have a zigzag shape (also appearing to have an "M") and undulate when Mario approaches them. There are only six Orange Juice Generators in the game.

Orange Juice Generator locations:
 * 1) Blocking the Warp Pipe leading to the Lily Pad Ride on a small island off the east coast of Delfino Plaza
 * 2) On the back of the police station's tower in Delfino Plaza, covering a small hole containing a Blue Coin
 * 3) On a tall building near the cannon leading to Pinna Park, covering a small hole with a Blue Coin in it
 * 4) Blocking the entrance to a cage containing a Shine Sprite in Episode 8 of Ricco Harbor
 * 5) Covering a Dune Bud to the left of the Sand Cabana in Gelato Beach
 * 6) On a flat green mushroom under Pianta Village in Episode 5, covering the entrance to a secret level

Electric goop
Electric goop, as its name states, is goop infused with electricity. Its color consists of a mixture of teal and yellow, and it has electricity visibly surging from it. This type of goop is found only in Sirena Beach. When Mario touches this goop, it will damage and briefly stun him. Touching it will also cause Mario's colors to be inverted momentarily. Because of their thick soles, Piantas are unharmed by the goop; Nokis are unharmed by the goop as well, though they will sink into it. In Episode 1 of Sirena Beach, the Manta covers a large portion of the beach in electric goop, causing Hotel Delfino to become stuck underground. After Mario defeats the Manta, the goop disappears and the hotel rises back out of the ground. The electric goop reappears in graffiti form in Episode 6, where it is shaped like a smiling Boo and covers most of the beach in front of Hotel Delfino. Mario has to clean all the goop off the beach within three minutes to earn a Shine Sprite.

Burning goop
Burning goop is lava-like goop found only in Pianta Village. It is red-orange in color, and it releases a small burst of flame every now and then. This type of goop burns Mario on contact and sends him flying upward, just like lava or fire. Thus, if Mario gets caught in the middle of a large quantity of this goop, he will likely lose a life or sustain heavy damage, as he will have nowhere else to go after flying upward and falling back downward. In Episode 1, this goop is produced by feverish Chain Chomplets. The goop reappears in Episode 3, where it covers almost the entire level and Mario must save the Pianta mayor from the fiery inferno. Coo Coos fly around and drop burning goop during this episode. The goop is also present in Episode 6, where Mario has to rescue ten Piantas that are stuck in small puddles of it. In Episode 7, Shadow Mario leaves a trail of burning goop behind him as he runs.

Slimy water
Slimy water is goop-polluted water that depletes one section of Mario's life meter about every two seconds that he is in it. It affects him only while he is on the surface of the water, and it does not hurt him while under the water. Slimy water appears in three areas in the game: Episode 6 of Bianco Hills, Episodes 1–5 of Ricco Harbor, and Episodes 1–4 of Noki Bay. The color and type of slimy water vary with the level in which it is encountered. In Bianco Hills, brownish goop covers the surface of the lake around the Big Windmill, making it poisonous. Ricco Harbor's slimy water, also classified as oil, comes from large quantities of spilled black goop that cover the surface of clean water in several areas. Noki Bay's translucent purple slimy water came about as a result of Eely-Mouth's gingivitis.

Hot water
Hot water (also described as gelatin) or ooze is toxic goop that is green in color. It essentially has the same properties as burning goop, but unlike burning goop, it cannot be removed or washed away, and it does not appear anywhere else in the game. Bowser and Bowser Jr. are found soaking in water in a giant floating hot tub at the top of Corona Mountain. They both remain in this goop for the duration of the final battle. During the battle, Bowser sometimes ground-pounds the hot tub to splash the water on Mario and damage him. There appears to be an unlimited amount of water in the hot tub; when Bowser tilts the tub, most of it falls out, but the supply is immediately replenished. After Mario ground-pounds all five sections that branch off from the hot tub, the entire hot tub tips over, and all of the water falls out of it into Corona Mountain. The large Shine Sprite that was trapped in the water is also set free.

Glorpedo
Glorpedoes, or Iga, are lumpy balls of goop that are pink, yellow, orange, and white in color and appear primarily in Episode 1 of Noki Bay, although Petey Piranha fires similar projectiles before his first fight. They are shot by a Monty Mole from a cannon positioned atop the large cork plugging up the waterfall. Mario will sustain damage if one runs into him. When Mario sprays them with water, they will grow in size. If sprayed long enough, they will explode, sometimes leaving behind a Water Bottle that Mario can collect to refill some of FLUDD's water. A Glorpedo will shrink back to its normal size if Mario does not continue spraying it. Glorpedoes will also explode if Mario jumps directly on top of them. After being fired from the Cannon, Glorpedoes roll along a set path all the way down the large cliff, trailing common goop behind them. They explode into goop when they reach the end of their path.

Super Mario 3D World + Bowser's Fury
Graffiti and goop reappear in the Bowser's Fury campaign of Super Mario 3D World + Bowser's Fury. Black splotchy goop can be found polluting the waters of Lake Lapcat, and it is present due to Fury Bowser, whom Bowser Jr. covered with the same goop. Sometimes, when the player finds Cat Shines, some goop in areas near the site of the Cat Shine disappears, usually revealing a new Cat Shine. However, Lake Lapcat cannot be completely cleansed of goop.

Attempting to swim in this goop results in Mario taking damage; this is unavoidable, as it negates the effects of all power-ups, including the Super Star and Invincibility Bell. If Plessie swims into the goop, it will dive below the water and resurface in an area without goop, leaving Mario to take damage. Small areas of goop can be traversed by utilizing the short invincibility granted after taking damage. If Mario attempts to leave the borders of the in-game map, an invisible border will prevent him from progressing. This border is also present around Fur Step Island before Giant Bowser is defeated at least once to prevent the player from re-accessing the area.

In the introductory cutscene of the campaign, Mario comes across a black M Grafitti that transforms into a portal, taking him to Lake Lapcat. Throughout the islands of Lake Lapcat, ?-shaped graffiti appears on various walls and surfaces. When Bowser Jr. joins Mario, he can use his Magic Paintbrush to create other graffiti art in these spots, yielding a reward once complete. While painting, he produces paint colored and textured like electric goop. In single-player mode, the player must either use the touch cursor or press when next to a graffiti spot to send Bowser Jr. to investigate. In multiplayer, only the second player can paint graffiti by approaching a graffiti spot and pressing. Once a graffiti spot has been painted, it will shine briefly before the shine fades. The art will remain in place of the ? mark permanently, but if the current save file is reloaded, the art will appear in black and white. If Bowser Jr. approaches the spot again, he will repaint the art in color, producing the same effect.

List of graffiti
The golden pipe in particular can be destroyed by Plessie, and if removed this way, it will not reappear until the current save file is reloaded. If entered, the pipe takes Mario to a bonus room filled with coins that he can use to add power-ups to the Item Storage. While the Warp Pipe can be reentered, the coins will not respawn until the save file is reloaded.

Minor appearances

 * In Mario Golf: Advance Tour, goop appears on the Mushroom Tourney course along with many Proto Piranhas.
 * In Mario Power Tennis, goop appears as an obstacle on the Delfino Plaza Court. It can cause players to slip and slide around. The player must also clear away goop in a tic-tac-toe-like minigame called Tic-Tac-Glow.
 * In Mario & Luigi: Paper Jam, during the Airplane Guard sequence of the battle with Petey Piranha, he attacks Mario and Luigi by spitting balls of goop as he does in Super Mario Sunshine.
 * In WarioWare Gold, F.L.U.D.D. is used to clean graffiti off a building in the Super Mario Sunshine microgame.
 * In Dr. Mario World, Dr. Petey Piranha uses goop to destroy viruses during his special skill animation.