Dungeons & Dragons is filled with countless monsters that a Dungeon Master can include in a given campaign. More monsters are added in almost every new D&D setting, giving DMs even more options to throw at their players. The monsters included in a campaign help set the tone and can also work to establish a specific location with the world. Some monsters can be found just about anywhere, but others are extremely specialized for certain environments.
Source：https://www.cbr.com/most-powerful-strongest-water-aquatic-monsters-dungeons-dragons/
