This chapter presents a new, annotated translation of an unusual treatise, commonly known by the Latin name De fluviis, preserved among the works of Plutarch and probably written between AD 100 and 250. The chapter introduction discusses the work’s date and authorship; notes the author’s preference for stories about Greece and places to the east as far afield as India, as well as his tendency to misidentify his literary sources when he does not actually invent them; and explains the repetitive organization of its 25 sections. These offer mythological explanations (often erotic, homicidal, or suicidal) for changes of names in rivers and mountains, as shaped by the recurrent themes of retribution and vindication of those who suffer injustice. On a factual level, the geography is lamentable, but the author’s examples of stones and plants with miraculous properties—often related to the fates of the individuals in the stories, though sometimes to the intrinsic properties of the rivers they feature—are sometimes confirmed by other sources. Presumably ‘the author knew his audience’.