Leeches

Leeches are a water-based swarming enemy in Rain World. They live solely in water and when found on land, will attempt to crawl back to the nearest body of water. If they fail to reach water quickly they dry out, wither away, and die. They will, however, respawn in the next cycle. Leeches come in two varieties: red and blue leeches. They are not a source of food, either dead or alive.

Behavior
When a living creature (excluding and other Leeches) enters the territory of Leeches, they swim after it, even occasionally jumping out of the water. A leech does not deal damage like a bite or explosion, but will instead attach itself to its prey and drag it down in an attempt to drown the creature. Once enough Leeches have latched on, a creature will be unable to ascend poles or swim to the surface for breath, depending on the strength of the creature. If attacked by Leeches, it is suggested the player reach dry land as soon as possible and shake them off by jumping back and forth left to right. If the player is on a pole, it is possible to balance on top and rock back and forth to shake them off. Dependent on the individual Leech, it turns black after a sufficient time out of water and lose grip on its prey. After drowning an entity the Leeches will continue to stay latched on for a short time, then let the body of their prey float to the surface and will ignore it.

Red Leeches
Red Leeches are the most common variety of Leech. They are a little smaller than and are found in pools of water in Drainage System and Garbage Wastes.

Blue Leeches
Blue Leeches are a bigger version of the Red Leech. They are harder to dehydrate out of water and are very fast and heavy. The Blue Leeches are found in the room before the gate from Garbage Wastes to Shoreline, and throughout Shoreline.

Strategy
Both varieties of Leech show interest any creature in the water (dead or alive), meaning it is possible to distract them with a pursuing predator or. It is also possible to use a to knock out the Leeches, or a small  to electrocute them.

, due to their high speeds and ability to jump out of the water, are very effective at dodging Leeches, especially in Shoreline. can be found in the room before the gate from Garbage Wastes to Shoreline, where there is a pool full of Blue Leeches. It is recommended to grab a white one and hop along the tops of the poles sticking out of the water.

If none of these options are available, as is usually the case in Drainage System, and swimming through them is the only available route, then:
 * Watch how they move. A Leech will only latch on during its boost. When pursuing you, make sure to dodge their short directional bursts. They can not change direction while boosting, so moving perpendicularly to a Leech is the best way to avoid it.
 * If there are too many Leeches to use the previous strategy, then speed up by repeatedly pressing the jump button underwater. Be careful though, as boosting underwater drains breath. This strategy is only viable in areas where it is possible to surface for air. In Shoreline, while traversing the long areas of open water where Blue Leeches stick in one place, you can wait for them to dive as far away as possible, press the jump button from a standstill on the surface to jump slightly out of the water, hold down, then press the jump button in rapid succession to quickly dive and swim under the water and bypass the Leeches. This is also useful in few other places, such as rooms in Drainage System that have pipes underwater in a pool of Leeches.
 * Allow a few Leeches to attach and have them fall off in a location where they will not pose a threat.
 * Squidcadas will actively 'fish' for Leeches by flying down to the water and allowing a few to attach, then flying away and dropping them near their nests. Bringing many Squidcadas to a pool of Leeches can get rid of the Leeches, but the Squidcadas may overwhelmed by them and be drowned.
 * Swimming along the surface of the water provides some extra buoyancy which can help keep Slugcat above water when being attacked by leeches. Popped also provide a small amount of buoyancy.

Trivia

 * Jetfish will attack Leeches in order to get food, but since they attack one leech at time, it is impractical to use this against a group of Leeches.
 * Once Leeches are done feeding on their prey, they begin searching for more food.
 * Unlike Leeches in real life, they do not seem to suck blood or even consume their prey. They instead leave it to float in the water and try to find something else to kill.