| ARAS | River forming part of the border between Azerbaijan and Iran |
| MADEIRA | Largest tributary of the Amazon river, forming part of the southern border of Brazil with Bolivia (7) |
| BUG | Tributary of the Narew River forming part of the Poland border with both Belarus and Ukraine (3) |
| TWEED | River, forming part of the border between Scotland and England, that enters the North Sea at Berwick |
| YALU | River forming part of the border between North Korea and China (4) |
| MOSELLE | River forming part of the border between Germany and Luxembourg (7) |
| OKAVANGO | River forming part of the border between Angola and Namibia (8) |
| ODER | River forming part of the border between Germany and Poland (4) |
| RENO | A river forming part of the border between Tuscany and Emilia-Romagna - or a city in Nevada (4) |
| URAL | River forming part of the boundary between Europe and Asia |
| TISZA | Major tributary of the Danube River, forming part of Ukraine's borders with Romania and Hungary (5) |
| KARA | River forming part of the European-Asian border |
| USSURI | River forming part of the Chinese border with Russia (6) |
| RIOGRANDE | Major river forming part of the Mexico-US border (3,6) |
| CAUCASUS | This mountain system lies between the Black Sea (which is to its west) and the Caspian Sea (which is to its east). It reaches across parts of Russia, Georgia, Azerbaijan, and Armenia. (8) |
| EMS | River forming part of the Germany-Netherlands boundary |
| LIMPOPO | Southern African river forming part of S Africanzimbabwe border |
| NIAGARA | River forming part of US-Canada border |
| NENE | River forming part of the Tyne network (4) |
| ZENANA | India and Iran: part of a house reserved for the women and girls (6) |
