This is a variant of a composition by Francken of which the prime version is that datable to the 1630s recorded by Dr. Ursula Härting in her monograph on the artist (Frans Francken der Jüngere, Freren, 1989, p. 314. no. 290, illustrated) and now in the Cleveland Museum of Art, Ohio. The Triumph of Neptune and Amphitrite was the subject of a number of variants by Francken and his studio (see ibid., pp. 310-5, nos. 276-98), although the arrangement of the figures of Neptune and Amphitrite of the Cleveland painting and the present work occur in only one other known example - and presumably the prototype for that element of the composition - in Kromeriz, Czech Republic (ibid., p. 311, no. 279). The subject of the painting was popular both for the fantastical aspect of the kingdom of the sea with its sea horses and flying fish, and the artistic opportunities presented by the goddess Amphitrite and her attendant naiads.
Alongside the Triumph, the Feast of Achelous is also included in the background on the upper right of the painting; that combination of themes occurs in almost all of Francken'’s depictinsn of the subject, and, indeed, in other examples in Francken's oeuvre the Feast is moved to the foreground as the primary subject: for example the painting in the Alte Pinakothek, Munich. Neither story is in fact connected to each other in Classical sources, however their juxtaposition in Francken's works probably derives from a part of the story of Achelous as related by Ovid in his Metamorphoses VIII.547 ff.: when the father of the naiad Perimele discovered that she had been seduced by the River God, he hurled his daughter from a cliff into the ocean; the unfortunate nymph was saved by the actions of Neptune, summoned by a plea of Achelous. The subsequent depiction of the entire retinue of Neptune is presumably an extrapolation of that event.