Water

Water is the most common hazard and obstacle in the Pikmin series, since it is presented mostly through bodies of water that are a part of the terrain itself. Water is a hazard to most Pikmin types, given that they cannot swim nor breathe underwater. The main exception to this is Blue Pikmin, which are unaffected, making this type of Pikmin ideal for underwater tasks. Bulbmin are also water-resistant, but are only found in caves. Winged Pikmin can also fly above the surface, making it possible to traverse bodies of water with them in the group, though they cannot be thrown when the leader they are following is underwater.

Bubbles of water that would choke other Pikmin also do nothing to Blue Pikmin and Bulbmin. Blue Pikmin that are pointed to drowning Pikmin will go to them, grab them, and throw them to shore, although Bulbmin will not.

Water in and of itself is not harmful to the Pikmin. Some bodies may be too shallow for the Pikmin to drown in, in which case they are completely harmless. Geysers also spew out water with immense force, but all Pikmin types can still ride them. Rain also has no adverse effect on the Pikmin.

In some games, leaders, Blue Pikmin, and Bulbmin stick to the bottom of the terrain while underwater, and gravity acts as if they were on land. In other games, Blue Pikmin have the ability to swim, allowing them the freedom to move up and down, such as when chasing aquatic enemies. Leaders will always remain on the ground, however, and when they throw a Blue Pikmin, said Pikmin will slowly ascend and descend while underwater.

Water can also be lethal to non-aquatic enemies, causing them to either lose health gradually or die quickly. Some enemies also react to water in different ways, such as fire-related enemies being extinguished or electric-related enemies electrifying water. Enemies that live in water usually become harmless when forced out of it.

As a hazard
Any inapt Pikmin type that touches water will begin flailing at the surface. They will eventually stop and drown, resulting in a Pikmin death. Pikmin in this state might be saved by having them slowly flail towards the leaders, and luring them to dry land. Pikmin in some games will follow leaders automatically, but in the other games, they must first be whistled. Alternatively, if there are idle Blue Pikmin nearby, they can toss drowning Pikmin onto land in some games.

Bodies of water are not the only way Pikmin can suffer from a water hazard. Some enemies have attacks that wet vulnerable Pikmin in such a way that a bubble of water forms around the top of their stem. This is enough to leave them choking and running in panic. If they're whistled in time, they will instantly return to normal, but if not, they will eventually collapse and die. These water attacks will cause damage to leaders as well and can knock them down.

Some bodies of water may cover the way to an important part of the area, where non-Blue Pikmin are needed. These pools might have a clog, which can be destroyed in order to drain the water, a bridge that can be built and used to cross over, or some lily pads can be taken to ride through and across a stream. Alternately, Winged Pikmin may be used, as they can fly above the surface of the water.

In Pikmin: Attack of the Breadbugs
Water is a hazard in Pikmin: Attack of the Breadbugs. Blue Pikmin are quite effective against water-based enemies and obstacles, since other Pikmin types would drown when exposed to them.

In Pikmin: Wide World
Water is one of the most common hazards appearing in Pikmin: Wide World, being found in many locations and utilized by a broad range of enemies. It is most common in Arid Oasis and Endless Sea. Blue Pikmin are resistant to water, and so are Blue Bulbmin and Wollymin. Winged Pikmin can fly over water, but will begin drowning if they are knocked into it. Captmin have partial resistance to water, as they can walk into a pool of water or get hit by it without harm so long as their faces are not exposed to it. Although they are related to Blue Pikmin, Green Pikmin are not resistant to water and will begin drowning in much the same way as most other Pikmin when exposed to it. Leaders can not drown and can not be hurt by water, although water-based attacks from enemies may push them around or knock them down. The Artificial Flippers allow leaders to swim in water. Because movement in water creates ripples, leaders, Pikmin, and even some enemies can be pushed around by it if the force is strong enough. Water can also be splashed around, which can be dangerous for inapt Pikmin, even ones on dry land.

Acid that falls into a body of water will be diluted by it and be rendered harmless, and water that falls into a body of acid will be diluted in much the same way. Enemies that are engulfed in flames can be extinguished when exposed to water, although usually it is partial and will not extinguish the parts of the creatures that are not submerged, necessitating the use of Red Pikmin. Some enemies that utilize electricity can electrify a body of water for as long as the two hazards remain in contact, which can have a multitude of effects, including, but not limited to: enemies in the water being severely injured or killed; leaders suffering heavy damage and being unable to move unless they are wearing the Anti-Electrifier; and lastly, any Pikmin that are drowning becoming paralyzed and inevitably dying. Some enemies that utilize ice can freeze water. Oil that is secreted over water will remain there and can be a particularly clingy and dangerous hazard, even for aquatic Pikmin.

Water can affect enemies in a variety of ways, and some enemies are only found in, on, or around water. Additionally, water, depending on its depth, can be beneficial, disadvantageous, or outright lethal to some enemies depending on their size and physiology, though some larger enemies are entirely unaffected by water in that they are not slowed by it nor can they realistically drown in it. Most aquatic enemies are harmless when forced out of the water, onto dry land, but they are still capable of flopping around to reenter a body of water if they can make it into one before they suffocate. Some aquatic enemies, however, can and will leap out of the water to eat Pikmin on the shore or above the surface. Some enemies are semiaquatic and are capable of surviving underwater, partially or wholly. Many land-treading enemies are unable to swim, and, depending on their size and the depth of a given pool of water, may begin to drown and eventually perish if they can not escape. Those that can swim will do so. Some enemies live on the water's surface but aren't themselves aquatic. Airborne enemies can float over water and are usually buoyant enough to float on the surface should they be weighted down, though some will be forced to swim, if they can, to dry land. Most mechanical enemies are entirely resistant to water, and some, like the Yellow Wollybot, can swim across the surface.

Aquatic Cannon Grubs launch from their mouth, in arcs, bubbles of water that follow the curvature of ground they land on, enveloping and drowning Pikmin in the way, until they hit an obstacle and burst open, releasing any trapped Pikmin. Caustic Dweevils release a shower of water from their body in self-defense. Fountain Crawmads spew streams of water at distant prey. Lesser Bubblimps and Greater Bubblimps are enveloped by bubbles of either water or acid. Skeeterskates and their relative, the Icewater Skeeterskate, spit balls of water at nearby Pikmin and leaders. Rainwisps release a drop of water onto Pikmin and leaders they fly over. Reef Blowhogs push underwater Pikmin and leaders around by blowing water at them. Splashing Skutterchucks splash Pikmin and leaders with water. Telescoping Pumphogs and Stone Pumphogs can shoot either fire or water. Watery Blowhogs and Watery Blowlets can spew water from their trunk, either in a steady stream or in bursts. Goolixes can freely enter a body of water and often use it to disguise themselves, but Chemical Goolixes and Nectar Goolixes that attempt this will respectively be gradually damaged or be killed instantly. The Grimacing Cremblub drools frequently, and it poses a drowning hazard. The Luring Slurker may suck up water and turn it into ice, which it lobs at its attackers. The Plasm Wraith may eject an Elemental Plasm that transforms into a giant bubble of water. Lastly, The Titan Dweevil, as one of its four hazard-based attacks, may turn blue before unleashing a massive torrent of water from its body. Although its name may suggest it is made of water, the Waterwraith's body can be safely touched by any Pikmin type.

Lily pads are always found on the water's surface and move along with the water's current if there is one. Weeping Posies release water when they are harmed. Blobs of black nectar, nectar, and spray nectar that fall into water will be diluted by it and disappear. Ultra-hot spray cannot be used underwater and, when used, cannot penetrate the water's surface. Every type of bomb rock, with the sole exceptions of mines and mine rocks, will become largely inoperative when exposed to water that submerges half the explosive. They can be thrown at enemies to inflict much damage but shatter after one use, making them somewhat like single-use rocks. The blast power and radius of a mine are the same regardless of whether it is on dry land or underwater, and mine rocks are much more effective underwater than on dry land. Clogs can be destroyed to drain a body of water. Water geysers and escape geysers eject a constant stream of water that propel leaders and Pikmin upward, although most need to be unclogged or activated before they can be used. Flukeweed dams are found above water and must be moved out of the way to allow lily pads to move a certain direction. Rain results in the formation of rain droplets, which collect on certain surfaces and can pose a drowning hazard to Pikmin they fall on.