# List of countries that border only one other country

"none" is preferred when the title is sufficiently descriptive; see [[WP:SDNONE]] This is a list of countries that have a land border with only one other country. Some on this list have a maritime border with additional countries. Some countries, which are not listed here, have no land border but do have a maritime border with a single other country, such as Sri Lanka.
There are generally three arrangements by which a country would have a single land border:
* an island divided between two states, such as between Haiti and the Dominican Republic, or between Ireland and the United Kingdom.
* a peninsula or a semi-enclave, where one country has a land border with a neighbouring one but is otherwise surrounded by sea, while the neighbour borders other countries—examples are Portugal (neighbouring Spain), The Gambia (surrounded by Senegal) and Brunei (surrounded by Malaysia). This applies to peninsulas, but also to non-peninsular nations like The Gambia and Brunei.
* the three countries forming a landlocked true enclave, surrounded by a larger country: San Marino and Vatican City (within Italy) and Lesotho (within South Africa).
Territory leased or ceded by one country to another for perpetual use, but not in sovereignty, such as Guantanamo Bay Naval Base in Cuba, or memorials, such as the American Cemetery in France, do not constitute true territorial borders because the land occupied remains a formal part of the host country.
This list is based on the Correlates of War Direct Contiguity data set, with maritime causeways and bridges not being counted.

## Countries bordering only one other country

This section considers only sovereign countries, not constituent countries like Wales and Scotland, which border only England.

### Landlocked

| Country | Neighbour | Border length | Border length | Notes |
| Country | Neighbour | km | mi | Notes |
| Lesotho | South Africa | 909 | 565 | Lesotho is an enclave which is entirely surrounded by South Africa. |
| San Marino | Italy | 39 | 24 | San Marino is an enclave entirely surrounded by Italy. |
| Vatican City | Italy | 3.2 | 2.0 | The Vatican City is an enclave entirely surrounded by Rome, Italy. |

### With coast

| Country | Neighbour | Border length | Border length | Notes |
| Country | Neighbour | km | mi | Notes |
| Brunei | Malaysia | 381 | 237 | Borders the Malaysian state of Sarawak on the island of Borneo. |
| Dominican Republic | Haiti | 360 | 220 | On the island of Hispaniola |
| The Gambia | Senegal | 740 | 460 | The Republic of the Gambia is bordered to the north, south and east by Senegal. |
| Haiti | Dominican Republic | 360 | 220 | On the island of Hispaniola |
| Republic of Ireland | United Kingdom | 360 | 220 | The Republic of Ireland borders the United Kingdom's Northern Ireland region on the island of Ireland. |
| Monaco | France | 4.4 | 2.7 | |
| Papua New Guinea | Indonesia | 820 | 510 | On the island of New Guinea |
| Portugal | Spain | 1,214 | 754 | |
| Qatar | Saudi Arabia | 60 | 37 | The planned Qatar–Bahrain Causeway would connect Qatar to Bahrain. |
| South Korea | North Korea | 238 | 148 | On the Korean Peninsula, at the Demarcation Line. The two countries are separated by a 4 km wide Demilitarized Zone. Both Koreas claim the Korean Peninsula. |
| Timor-Leste | Indonesia | 228 | 142 | On the island of Timor. |
| United Kingdom | Republic of Ireland | 360 | 220 | On the island of Ireland. The British Overseas Territories of Gibraltar and Akrotiri and Dhekelia border Spain and Cyprus respectively, but these territories are part of the United Kingdom so add them proper (see #Dependent territories section). |

## Causeways, bridges, and tunnels

Often called fixed crossings or fixed links, transportation corridors constructed to cross bodies of water without any intermittent connections such as ferries or ships may be between different states. These may be considered artificial "persistent" borderpoints for land vehicles or pedestrians, but are not typically considered land borders given their need for continuous operation and maintenance, as well as their ease of volume control or closure by either state. Two countries are islands and have no land borders, but maintain fixed borderpoints with other nations.
| Country | Land neighbour | Borderpoint neighbour | Notes |
| Country | Land neighbour | Borderpoint neighbour | Notes | United Kingdom | Republic of Ireland | France | In addition to its border with Ireland, has a fixed link with France in the Channel Tunnel. |
| Bahrain | None, Since Bahrain is an island. | Saudi Arabia | Although an island nation with no natural land borders, Bahrain maintains persistent connection to Saudi Arabia by the King Fahd Causeway at Passport Island. |
| Singapore | None, Since Singapore is cut off by a strait. (Specifically, the Strait of Johor.) | Malaysia | Although an island nation with no natural land borders, Singapore maintains persistent connections to Malaysia by the Johor Causeway and the Malaysia–Singapore Second Link. |

## Dependent territories

In some cases, a dependent territory of one nation borders another nation.
| Territory | Sovereignty | Neighbour | Border length | Notes |
| Territory | Sovereignty | Neighbour | km | Notes |
| Akrotiri and Dhekelia | United Kingdom | Cyprus | 108 | British sovereign base areas, border the Republic of Cyprus. Dhekelia also borders the Turkish Republic of Northern Cyprus, but the latter is recognised only by Turkey. |
| Gibraltar | United Kingdom | Spain | 1.2 | A British overseas territory, occupies a small peninsula and has a 1.2 km (0.75 mi) land border with Spain. Spain claims some of Gibraltar as its own territory. |
| Ross Dependency | New Zealand | Australia | | New Zealand's (largely unrecognised) territorial claim in Antarctica borders only the Australian Antarctic Territory and the unclaimed Marie Byrd Land. (It also touches other claims at the South Pole.) |

## Integral parts of sovereign states

In most cases, an integral part of a larger country shares a border with another nation.
| Territory | Sovereignty | Neighbour | Border length | Notes |
| Territory | Sovereignty | Neighbour | Åland | Notes | Finland | Sweden | 528,60 m | Autonomous region of Finland. Åland had a dispute in Market Island. |
| French Southern and Antarctic Lands | France | Australia | 5.533.470,05 m | Adélie Land, France's (largely unrecognised) claim in Antarctica borders only the Australian Antarctic Territory. (It also touches other claims at the South Pole.) |
| Greenland | Kingdom of Denmark | Canada | 1,280 m | A constituent country of the Kingdom of Denmark, Greenland had a border dispute with Canada regarding uninhabited Hans Island. The island is located in the centre of the Kennedy Channel of Nares Strait (between Canada's Ellesmere Island and northern Greenland), which constitutes the agreed maritime border. On June 11, 2022, both countries signed an agreement to split the island, which will come into effect as soon as the parliaments of Canada, Denmark, Greenland, and Nunavut ratify it. |
| Saint Martin | France | Kingdom of the Netherlands | 16 km | The island is split between two island territories: the northern half, Saint-Martin, is a French overseas collectivity; the southern half, Sint Maarten, is a constituent country of the Kingdom of the Netherlands. |
| Sint Maarten | Kingdom of the Netherlands | France | 16 km | The island is split between two island territories: the northern half, Saint-Martin, is a French overseas collectivity; the southern half, Sint Maarten, is a constituent country of the Kingdom of the Netherlands. |

## Historical

Many countries historically had only one neighbour. Some no longer exist while others now have either no land borders or borders with more than one nation due to border changes.
* Canada: bordered only by the United States until 2022, it now shares a short border with the Kingdom of Denmark at Hans Island, with Canada's Nunavut on one side and Denmark's Greenland on the other side.
* Kingdom of Denmark: bordered only by Germany (with a causeway connecting it to Sweden) until 2022 (the constituent country of Denmark still only borders Germany), it now shares a short border with Canada at Hans Island, with Canada's Nunavut on one side and Denmark's Greenland on the other side.
* Korea: bordered only China for several hundred years before 1860, after which a second international border with Russia appeared (approx. 17 km (11 mi) long), according to the Convention of Peking. Following the division of Korea in 1945 only North Korea now shares this border.
* Ciskei: one of the Bantustans of South Africa; created under apartheid, reincorporated on April 27, 1994.
* Venda: another Bantustan, Venda was a true enclave bordering only South Africa and separated narrowly from Zimbabwe by the Madimbo corridor to the north; reincorporated on April 27, 1994.
* Newfoundland: with Canada, until March 31, 1949, when it became the Canadian province of Newfoundland (now named Newfoundland and Labrador).
* Scotland and England: bordered each other until 1707 when they were united as Great Britain by the Acts of Union, see Anglo-Scottish border.
* Japan: bordered Russia on the island of Sakhalin from 1905 until 1910, until Japan inherited the China–North Korea border and the North Korea–Russia border upon the Japanese annexation of Korea. Both Sakhalin and Korea were relinquished after Japan's defeat in World War II in 1945. (See Karafuto Prefecture and Empire of Japan).
* Weihaiwei: 1898–1930, British colony on a leased territory from China's Qing dynasty. Transferred to the Republic of China in 1930.
* Tasmania: bordered only by the Colony of Victoria (on Boundary Islet), until the federation of the Commonwealth of Australia in 1901.
* Hong Kong: bordered China 1860–1997 as a crown colony of the United Kingdom. Transferred to the People's Republic of China in 1997.
* Macau: bordered China until 1999 as a colony of Portugal. Transferred to the People's Republic of China in 1999.