| River that flows into the Bay of Bengal | 39 |
| River that flows by the Hermitage Museum | 40 |
| River that flows by the Hermitage | 33 |
| River that flooded Florence in 1966 | 35 |
| River that feeds the Ubangi | 27 |
| River that feeds the Missouri | 29 |
| River that feeds the Caspian Sea | 32 |
| River that ends in Tarragona | 28 |
| River that ends at Yuma | 23 |
| River that ends at Cairo | 24 |
| River that empties into the Firth of Clyde | 42 |
| River that empties into the Caspian | 35 |
| River that empties into the Bering Sea | 38 |
| River that drains the western Pyrenees | 38 |
| River that drains the Lake of Thun | 34 |
| River that drains the Everglades into Biscayne Bay | 50 |
| River that drains more than 20% of France | 41 |
| River that divided the Romans and the Carthaginians | 51 |
| River that crosses the border of Russia and Kazakhstan | 54 |
| River that causes people to forget | 34 |
| River that can be seen from the Uffizi Gallery | 46 |
| River that begins in Pittsburgh | 31 |
| River that begins in Nord | 25 |
| River that all travelers forget about after going down it | 57 |
| River that "sweats oil and tar" in T. S. Eliot's "The Waste Land" | 89 |
| River target of the first Egyptian plague | 41 |
| River suspension | 16 |
| River surrounding Notre Dame | 28 |
| River surrounding Navy Island | 29 |
| River Styx V.I.P. | 17 |
| River structure | 15 |
| River straddled by Florence | 27 |
| River straddled by Basel, Switzerland | 37 |
| River stoppers | 14 |
| River stopper | 13 |
| River starting in Switzerland | 29 |
| River sporting activity | 23 |
| River sport | 11 |
| River spanner | 13 |
| River spanned by the Three Gorges Dam | 37 |
| River spanned by the Ponte Vecchio | 34 |
| River spanned by the Pont Neuf | 30 |
| River spanned by the Key Bridge | 31 |
| River spanned by the Brooklyn Bridge | 36 |
| River spanned by the Bagnell Dam | 32 |
| River spanned by La Pont Neuf | 29 |
| River south of Minsk | 20 |
| River south of Kassel | 21 |
| River source | 12 |
| River skipper | 13 |
| River sight | 11 |
| River Shannon's Lough ___ | 29 |
| River setting for "The Wind in the Willows" | 53 |
| River setting | 13 |
| River separating Queens from the Bronx | 38 |
| River separating Ontario and Quebec | 35 |
| River separating Germany and Poland | 35 |
| River separating continents | 27 |
| River seen while "sur le pont d'Avignon" | 54 |
| River seen from Windsor Castle | 30 |
| River seen from the Eiffel Tower | 32 |
| River seen from Lorelei Rock | 28 |
| River seen from Ciudad BolÃvar | 33 |
| River seen from Bern | 20 |
| River sediment | 14 |
| River section | 13 |
| River sacred to over a billion | 30 |
| River runner | 12 |
| River rompers | 13 |
| River romper | 12 |
| River rodent | 12 |
| River rising through the Bernese Alps | 37 |
| River rising in Tibet | 21 |
| River rising in the Vosges Mountains on the border of Alsace-Lorraine | 69 |
| River rising in the Vosges Mountains | 36 |
| River rising in the Urals | 25 |
| River rising in the Rocky Mountains | 35 |
| River rising in the Grampians | 29 |
| River rising in the Carpathians | 31 |
| River rising in the Cantabrian Mountains | 40 |
| River rising in the Bernese Alps | 32 |
| River rising in the Ardennes Mountains | 38 |
| River rising in the Ardennes | 28 |
| River rising in Silesia | 23 |
| River rising in Mongolia | 24 |
| River rising in Bavaria | 23 |
| River restrainers | 17 |
| River residue | 13 |
| River resident | 14 |
| River rental | 12 |
| River regulators | 16 |
| River regulator | 15 |
| River reflection | 16 |
| River rat | 9 |
| River rapids | 12 |
| River rapid | 11 |
| River racer | 11 |
| River quay | 10 |
| River pronounced "waz" | 32 |
| River projects | 14 |