Naiads

Naiads, River Nymphs or Water Spirits were the gods and goddesses who lived in rivers and streams.

They were most commonly found in the Great River of Narnia. They are human-like in appearance, and are spiritually tied to the waters of Narnia. No physical description is given, but in illustrations by Pauline Baynes, they are depicted as pretty women dressed in gowns of aquatic colors, most commonly in blue, and sometimes wearing crowns of rushes around their heads.

Their father and chief was the River god, who had a weedy beard. Other River Gods do exist, and are the male equivilant of Naiads.

In The Magician's Nephew, they are described as rising out of the river, along with the River God, and they carried Queen Helen's train at her coronation. In The Lion, the Witch and the Wardrobe (book), they are mentioned among Aslan's followers at the Stone Table. In Prince Caspian (book), they were awoken by Aslan at the beginning of the reign of Caspian X, to help fight against the Telmarines.

Despite them being mentioned in the books, they were not depicted in the first two films, except for the River God who appeared in Prince Caspian, but finally the Naiads appeared in the third one, The Chronicles of Narnia: The Voyage of the Dawn Treader (film), as replacements for the Merpeople.

In the film, they are portrayed in a similiar manner to the Dryads, in the respect that they are non-physical beings that use their element as their bodies, which in this case would be water.