Which country is the only one to be surrounded by a single country on all four sides?

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: for example Denmark "borders" by sea Sweden, Norway and Canada (between Greenland and Baffin Island); while, in addition to Denmark, Canada also has a sea boundary with France (between the island of Newfoundland and the territory of St. Pierre and Miquelon).

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.