Naiads are water nymphs, usually connected to a certain spring, well, brook, or stream. It was believed that if a naiad’s spring or well dried up, that the Naiad would die.
Like most Naiads are playful, but can be deadly to humans. They enjoy beauty, but are also quite jealous, so if they lure a human underwater, they’re likely to keep it there—and drown it. The Naiads are either descended from Poseidon, or from Oceanids (the 3000 daughters of the Titans Oceanus and Tethys). Oceanids are similar creatures, but associated with salt water, as Naiads are associated with fresh.
Naiads were often the focus of cults or rituals in archaic times, with belief that they were tied to fertility or cleansing. Children coming-of-age would throw locks of their hair into a spring dedicated to a Naiad, and in some cases Oracles or ritualistic animal drownings were tied to a certain spring as well.