A.T. Robertson Commentary Revelation 17:15

"And he saith unto me, The waters which thou sawest, where the harlot sitteth, are peoples, and multitudes, and nations, and tongues." — Revelation 17:15 (ASV)

Where the harlot sitteth (ου η πορνος καθητα). Relative adverb ου (where) referring to the waters (υδατα) of verse 1 on which the harlot sits. Present middle indicative of καθημα.

Are peoples, and multitudes, and nations, and tongues (λαο κα οχλο εισιν κα εθνη κα γλωσσα). The O.T. uses "waters" as symbol for "peoples" (Isaiah 8:7; Jeremiah 47:2; Psalms 29:10, etc.). "Rome's greatest danger lay in the multitudes which were under her sway" (Swete).