There are 15 countries around the world that have a land border with only one other country, with six of them in Europe.
There are typically three ways in which a country would have just a single land border. It might be an island divided between two states, such as Ireland and the UK.
It might be a peninsula or a semi-enclave mainly surrounded by sea but with one land border, such as Portugal and Spain. Lastly, landlocked countries may form an enclave surrounded by a larger country, such as San Marino and the Vatican City within Italy.
The list has been created based on data from the Correlates of War Direct Contiguity, with maritime causeways and bridges not being counted.
In terms of landlocked countries with only one land border, there are only three: Lesotho, San Marino, and Vatican City. All three are enclaves – Lesotho surrounded by South Africa, and San Marino and the Vatican surrounded by Italy.
Many more countries have coastlines that also only share a land border with one other country, with 12 making the list according to the Correlates of War Direct Contiguity.
In Asia, Brunei borders the Malaysian state of Sarawak on the island of Borneo. In Africa, The Gambia is bordered to the north, south, and east by Senegal. In Europe, Monaco’s one neighbour is France, and Portugal just shares a land border with Spain.
One current example that could change in the future is Qatar and its border with Saudi Arabia. The proposed Qatar-Bahrain Causeway would connect the two countries, taking Qatar off the list.
Closer to home, the Republic of Ireland borders the UK’s Northern Ireland region on the island of Ireland. The reason Wales and Scotland aren’t on the list is because it only considers sovereign countries, not constituent countries.