| River herring | 13 |
| River hazards | 13 |
| River hazard | 12 |
| River growth | 12 |
| River gamboler | 14 |
| River from the Vosges Mountains | 31 |
| River from the Savoy Alps | 25 |
| River from the Cantabrian Mountains | 35 |
| River from the Cairngorm Mountains | 34 |
| River from the Bernese Alps | 27 |
| River from the Alps to the North Sea | 36 |
| River from the Alps | 19 |
| River from Superior to Huron | 28 |
| River from Staffordshire | 24 |
| River from Silesia to the Neisse | 32 |
| River from Pittsburgh to the Mississippi | 40 |
| River from Pittsburgh | 21 |
| River from Lake Victoria | 24 |
| River from Lake Ontario | 23 |
| River from Lake Ladoga | 22 |
| River from Lake Erie to Lake Ontario | 36 |
| River from Lake Erie | 20 |
| River from Dijon | 16 |
| River from Belgium to France | 28 |
| River frolicking? | 17 |
| River frolickers | 16 |
| River frolicker | 15 |
| River found in "sewer" | 32 |
| River forming the Handegg waterfall | 35 |
| River forming the eastern border of Charlemagne's empire | 60 |
| River forming the borders of parts of five states | 49 |
| River forming part of the Germany-Netherlands boundary | 54 |
| River forming part of the European-Asian border | 47 |
| River forming part of Germany's eastern border | 50 |
| River formed near Fort Wayne | 28 |
| River formed by the junction of the Fulda and Werra | 51 |
| River formed by the Congaree and Wateree | 40 |
| River formed at Pittsburgh | 26 |
| River formations | 16 |
| River formation | 15 |
| River forest firth | 18 |
| River for the young Moses | 25 |
| River for some boatmen | 22 |
| River for poet Masters | 22 |
| River for Burns | 15 |
| River followed by the Pony Express | 34 |
| River followed by the Oregon Trail | 34 |
| River flowing to the Seine | 26 |
| River flowing to the Rhine | 26 |
| River flowing to the Missouri | 29 |
| River flowing to Rennes | 23 |
| River flowing through Zaragoza | 30 |
| River flowing through Venezuela | 31 |
| River flowing through Kazakhstan | 32 |
| River flowing through Ghent | 27 |
| River flowing into the Severn | 29 |
| River flowing into the Seine | 28 |
| River flowing into the Rhine | 28 |
| River flowing into the Ouse | 27 |
| River flowing into the Oise | 27 |
| River flowing into and out of Lake Geneva | 41 |
| River flowing from France into Germany | 38 |
| River flowing between two Great Lakes | 37 |
| River flowing beneath Paris's Pont Neuf | 43 |
| River flowing alongside Notre Dame | 34 |
| River floater | 13 |
| River float, at times | 21 |
| River fish | 10 |
| River ferried by Charon | 23 |
| River feeding | 13 |
| River feeders | 13 |
| River feeder: Abbr. | 19 |
| River feeder | 12 |
| River fed by the Wabash | 23 |
| River fed by the Porcupine | 26 |
| River features | 14 |
| River featured in Guinness flick | 32 |
| River featured in "The Ten Commandments" | 50 |
| River feature | 13 |
| River famously crossed by Caesar | 32 |
| River facetiously described as "a mile wide at the mouth, but only six inches deep" | 93 |
| River explored by V. L. Cameron et al. | 38 |
| River explored by David Livingstone | 35 |
| River entering the Fulda | 24 |
| River ends? | 11 |
| River ending at the Dead Sea | 28 |
| River ending at Ghent | 21 |
| River encircling Hades | 22 |
| River emptying into Green Bay | 29 |
| River embankments | 17 |
| River embankment | 16 |
| River ducks | 11 |
| River duck | 10 |
| River drops | 11 |
| River drainage area | 19 |
| River down under? | 17 |
| River down under | 16 |
| River dot | 9 |
| River dividing New York City | 28 |
| River dividing Germany and Poland | 33 |