Artist's rendering of Sachamama, an aquatic cryptid


Traditional depiction of a aquatic-based cryptid (Mali), from an adobe structure near the Niger River


Giant fish, such as this one, are reported.

Category of Cryptids  that have lived or have been seen in aquatic environment. An aquatic environment consist of an ecosystem dependent (or partially independent) of some body of water (aquatic ecosystems). The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems (including lakes and rivers).

An aquatic cryptid is an creature, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that live in them can be categorized as aquatic (water) or terrestrial (land). Animals that move readily from water to land and vice versa are referred to as amphibians.

The term aquatic can in theory be applied to cryptids that live in either freshwater (freshwater animals) or saltwater (marine animals). However, the adjective marine is most commonly used for animals that live in saltwater.