| 100% | AMUR | 4 | River that forms the boundary between Manchuria and Russia |
| 71% | DRINA | 5 | River that forms the boundary between Bosnia and Herzegovina and Montenegro |
| 67% | TWRCH | 5 | River that formed the ancient boundary between Brecknockshire and Carmarthenshire |
| 60% | MORAVA | 6 | River that forms the border between Slovakia and Austria |
| 60% | MEKONG | 6 | River that forms the border between Laos and Myanmar |
| 59% | ORANGE | 6 | River rising in the Drakensberg mountains that forms the boundary between South Africa and Namibia |
| 57% | DRINA | 5 | River forming the boundary between Bosnia and Herzegovina and Montenegro |
| 56% | ODER | 4 | River that forms part of the border between Germany and Poland |
| 56% | TAMAR | 5 | River that forms most of the border between Cornwall and Devon |
| 56% | ORINOCO | 7 | River that forms part of the border between Colombia and Venezuela |
| 56% | MOSELLE | 7 | River that forms part of the border between Germany and Luxembourg |
| 56% | DOURO | 5 | River that forms part of the border between Spain and Portugal |
| 56% | RIONEGRO | 8 | River that forms part of the border between Colombia and Venezuela |
| 55% | ELBE | 4 | River that formed part of the border between East and West Germany |
| 55% | RUBICON | 7 | Stream that formed the ancient boundary between Italy and Cisalpine Gaul |
| 54% | YALU | 4 | River that forms a large part of the border between North Korea and China |
| 53% | DOURO | 5 | River that forms part of the border between Spain and Portugal before flowing west to the Atlantic |
| 52% | RHYMNEY | 7 | River in Wales forming the boundary between the historic counties of Glamorgan and Monmouthshire |
| 52% | URAL | 4 | River forming part of the boundary between Europe and Asia |
| 48% | DEE | 3 | River that forms part of the England/Wales boundary |
| 46% | LIMPOPO | 7 | River forming the border between Zimbabwe and South Africa |
| 45% | KASAI | 5 | Tributary of the Congo River that forms part of the border between the Democratic Republic of the Congo and Angola |
| 45% | EBRO | 4 | River that was the ancient dividing line between Rome and Carthage |
| 44% | AMURRIVER | 9 | Major river between Russia and Manchuria |
| 43% | WAVENEY | 7 | River forming the eastern border between Norfolk and Suffolk |
| 42% | STMARYS | 7 | River that forms the Michigan-Ontario border |
| 41% | ERIE | 4 | Canal that forms a link between the Atlantic and the Great Lakes |
| 40% | WYE | 3 | Maryland river that lent its name to the memorandum negotiated between Israel and the Palestinian Authority in 1998 |
| 40% | ARAS | 4 | River forming part of the border between Azerbaijan and Iran |
| 40% | MOSELLE | 7 | River forming part of the border between Germany and Luxembourg |