| 100% | DEE | 3 | River that forms part of the England/Wales boundary |
| 68% | GUADIANA | 8 | River that forms part of the Spain-Portugal border |
| 68% | RHINE | 5 | River that forms part of the France/Germany border |
| 68% | WABASH | 6 | River that forms part of the Illinois-Indiana border |
| 68% | NIAGARA | 7 | River that forms part of the U.S.-Canada border |
| 67% | ODER | 4 | River that forms part of the border between Germany and Poland |
| 67% | ORINOCO | 7 | River that forms part of the border between Colombia and Venezuela |
| 67% | MOSELLE | 7 | River that forms part of the border between Germany and Luxembourg |
| 67% | DOURO | 5 | River that forms part of the border between Spain and Portugal |
| 67% | RIONEGRO | 8 | River that forms part of the border between Colombia and Venezuela |
| 67% | ELBE | 4 | River that formed part of the border between East and West Germany |
| 65% | URALS | 5 | Mountains that form part of the Asia/Europe boundary |
| 64% | DOURO | 5 | River that forms part of the border between Spain and Portugal before flowing west to the Atlantic |
| 62% | EMS | 3 | River forming part of the Germany-Netherlands boundary |
| 61% | URAL | 4 | River forming part of the boundary between Europe and Asia |
| 58% | YALU | 4 | River that forms a large part of the border between North Korea and China |
| 57% | MAMORE | 6 | River rising in the Andes that forms part of the Bolivia-Brazil border |
| 56% | ULNA | 4 | Bone that forms part of the forearm |
| 55% | KASAI | 5 | Tributary of the Congo River that forms part of the border between the Democratic Republic of the Congo and Angola |
| 54% | MONTE | 5 | Town and resort that forms part of the principality of Monaco |
| 54% | MEKONG | 6 | River that forms much of the Laos/Thailand border |
| 54% | RHYMNEY | 7 | River in Wales forming the boundary between the historic counties of Glamorgan and Monmouthshire |
| 53% | TAMAR | 5 | River that forms most of the border between Cornwall and Devon |
| 52% | AMUR | 4 | River that forms the boundary between Manchuria and Russia |
| 51% | TWRCH | 5 | River that formed the ancient boundary between Brecknockshire and Carmarthenshire |
| 51% | ARAS | 4 | River forming part of the border between Azerbaijan and Iran |
| 51% | MOSELLE | 7 | River forming part of the border between Germany and Luxembourg |
| 51% | OHIO | 4 | River that formed an extension of the Mason-Dixon line |
| 51% | DRINA | 5 | River that forms the boundary between Bosnia and Herzegovina and Montenegro |
| 50% | AGNUSDEI | 8 | Chant forming part of the Roman Catholic Mass that is translated as Lamb of God |