Naiads are female spirits presiding over fountains, wells, springs, streams, brooks and other bodies of fresh water.

Naiads were associated with fresh water, as the Oceanids were with saltwater and the Nereids specifically with the Mediterranean, but because the ancient Greeks thought of the world’s waters as all one system, which percolated in from the sea in deep cavernous spaces within the earth, there was some overlap. Arethusa, the nymph of a spring, could make her way through subterranean flows from the Peloponnese, to surface on the island of Sicily.