Smallest shared island (inhabited)
Saint-Martin (Saint Martin), Sint Maarten (Saint Martin)
87 square kilometre(s)
Not Applicable ()

Covering an area of just 87 km² (33 sq miles), Saint Martin in the Leeward group of the Lesser Antilles is the smallest populated island to be shared between two nations. Since 1648, the Caribbean retreat has been divided between the French-owned Saint-Martin in the north and the Dutch-owned Sint Maarten in the south.

Saint Martin's pre-colonial name was Oualichi – “Island of women.” With the signing of the Treaty of Concordia in 1648, the island was split roughly 60:40, with the French awarded 53 km² (20 sq mi) and the Dutch awarded 34 km² (13 sq mi). As of 2009, it's home to a population of 77,741 - 40,917 Dutch and 36,824 French. Saint-Martin is considered an overseas collectivity of France, while Sint-Maartin is designated as one of the four countries in the Kingdom of the Netherlands.

The shared islands of Koiluoto (Finland and Russia) and Märket (Sweden and Finland) are, at 0.03 km² (0.01 sq mi), the smallest without a permanent human population. Adam's Bridge - a chain of shoals and sand banks shared by Sri Lanka and India - might also be a contender for the unpopulated record, depending on one's definition of "island", as might K Island (aka Nova Zemlya Island), a 7-km-long (4.3-mi) sand island in the Black Sea divided between Romania and Ukraine.