| River to the Mississippi | 24 |
| River to the Missouri | 21 |
| River to the Moray Firth | 24 |
| River to the Mosel | 18 |
| River to the Moselle | 20 |
| River to the North Sea | 22 |
| River to the Oder | 17 |
| River to the Ohio | 17 |
| River to the Oise | 17 |
| River to the Ouse | 17 |
| River to the Raba | 17 |
| River to the Rhein | 18 |
| River to the Rhine | 18 |
| River to the Rhone | 18 |
| River to the Rio Grande | 23 |
| River to the Rybinsk Reservoir | 30 |
| River to the Sea of Okhotsk | 27 |
| River to the sea, in French | 27 |
| River to the Seine | 18 |
| River to the Severn | 19 |
| River to the Snake | 18 |
| River to the South China Sea | 28 |
| River to the St. Lawrence | 25 |
| River to the Tigris | 19 |
| River to the Trent | 18 |
| River to the Tyrrhenian Sea | 27 |
| River to the Ubangi | 19 |
| River to the underworld | 23 |
| River to the Vistula | 20 |
| River to the Volga | 18 |
| River to the Volga near Gorky | 29 |
| River to The Wash | 17 |
| River to the Yangtze | 20 |
| River to the Yellow Sea | 23 |
| River to Volga | 14 |
| River to Winyah Bay | 19 |
| River to Yangtze | 16 |
| River to Yellow Sea | 19 |
| River too big for its breaches | 30 |
| River tower | 11 |
| River transport | 15 |
| River transports | 16 |
| River triangle | 14 |
| River tributary | 15 |
| River tributary, often | 22 |
| River tug | 9 |
| River under Florence's Ponte Vecchio | 40 |
| River under London Bridge, once | 31 |
| River under the Brooklyn Bridge | 31 |
| River under the Peace Bridge | 28 |
| River under the Ponte Santa Trinita | 35 |
| River under the Ponte Sisto | 27 |
| River under the Ponte Vecchio | 29 |
| River valley | 12 |
| River valley formation | 22 |
| River valley known for Riesling wine | 36 |
| River valley silt | 17 |
| River valleys | 13 |
| River vehicle | 13 |
| River vehicles with engines | 27 |
| River vessel | 12 |
| River vessels | 13 |
| River viewed from Amboise | 25 |
| River visible from the Uffizi Gallery | 37 |
| River vortex | 12 |
| River walls | 11 |
| River waterfall | 15 |
| River west of the Arabian Desert | 32 |
| River west of the Nubian Desert | 31 |
| River where baby Moses was found | 32 |
| River where Moses was hidden as a baby | 38 |
| River where Rome was founded | 28 |
| River where Romulus and Remus were abandoned | 44 |
| River where the Oto once settled | 32 |
| River whose delta is Cape Tortosa | 33 |
| River whose headwaters are near Lake Baikal | 43 |
| River whose mouth is near Nieuwpoort | 36 |
| River whose name is Celtic for "river" | 48 |
| River whose name means "hateful" | 42 |
| River whose name means "river" | 40 |
| River whose source is Mount Saint Helena | 40 |
| River with a chateau-filled valley | 34 |
| River with a fragrant sound | 27 |
| River with a mouth in the Mediterranean | 39 |
| River with a sturgeon population | 32 |
| River with an alphabetical-sounding name | 40 |
| River with an ancient road leading to Stonehenge | 48 |
| River with Blue and White tributaries | 37 |
| River with famous falls | 23 |
| River with historic flooding in 1966 | 36 |
| River with its source in the Appalachians | 41 |
| River with the Reichenbach Falls | 32 |
| River wriggler | 14 |
| River zapper | 12 |
| River ___ | 9 |
| River ___ (old Atari game) | 26 |
| River's "My Own Private Idaho" co-star | 52 |
| River's "My Own Private Idaho" costar | 51 |
| River's beginning | 21 |
| River's bottom | 18 |