Water fern is a common name for several plants and may refer to:
Salviniales, an order of aquatic ferns
Azolla filiculoides
Blechnum cartilagineum, or soft water fern
Blechnum chambersii, lance water fern
Blechnum fluviatile, or ray water fern
Blechnum indicum, or swamp water fern
Blechnum nudum, or fishbone water fern
Blechnum patersonii, or strap water fern
Blechnum penna-marina, or alpine water fern
Blechnum wattsii, or hard water fern
Bolbitis heudelotii, or African water fern
Histiopteris incisa
Osmunda regalis
Regnellidium diphyllum, or two-leaf water fern
Salvinia molesta, or giant water fern
