The cult of river-goddesses is widely attested in Ireland, Britain and Gaul by ancient literary texts, epigraphic devices and votive offerings discovered at places of worship where the goddesses used to be honoured. River deification is not limited to female figures: important river gods are known from inscriptions discovered in Gaul and Germany, such as Rhenos, the god personifying the Rhine, or Danuvios, the god of the Danube.1746 Nevertheless, river-goddesses predominate, certainly because rivers were regarded as mothers fertilizing the fields and nurturing the peoples. In Ireland, the tradition of river-goddesses is well-attested. The chief rivers of Ireland were deified: the Odras as the goddess Odras, the Boyne as the goddess Bóinn, the Shanonn as the goddess Sionann, the Inny as the goddess Eithne and the Érne as the goddess Érne. Their respective legends hinge on a similar theme, which is that of the drowning of the lady in the river. In Gaul and Britain appears the same concept of a goddess bearing the name of the river and personifying its waters: Sequana presides over the Seine, Matrona over the Marne, Souconna over the Saône, Icauni over the Yonne and Verbeia over the Wharfe. Their worship in Gallo-Roman times is evidenced by inscriptions, water sanctuaries and votive offerings, generally unearthed at the sources of the rivers. There is no doubt about their Celticity: their names, even though their origins sometimes remain obscure, are unmistakably Celtic.
Inscriptions dedicated to the god Rhenus: CIL XIII, 5255 (Eschenz), CIL XIII, 7790, 7791 (Remagen), CIL XIII, 8810, 8811 (Wiltenburg), AE 1969/1970, 434 (Strasbourg). Inscriptions dedicated to the god Danuvios: CIL III, 11804 (Mengen, Germany), CIL III, 5863 (Rissitissen, Germany), CIL III, 3416, 10395 (Alt-Ofen, Hungary) and CIL III, 10263 (Osijek, Croatia). Diodorus Siculus, in his Historical Library (V, 25, 31), refers to the Danube as Danoubios. See also Bourgeois, 1991, pp. 33-34 ; Olmsted, 1994, p. 439 ; Lacroix, 2007, pp. 47-49.