The bizarre European island in the middle of a river that swaps nationality every 6 months

A small, uninhabited island in Europe continues one of the continent's strangest traditions (Image: Getty)

Nestled in the Bidasoa River between Spain and France lies a tiny, uninhabited island that boasts a bizarre political arrangement - changing nationality twice a year. Pheasant Island, which sits on the border between the French town of Hendaye and the Spanish town of Irun, alternates sovereignty every six months. From February to July, Spain oversees the island, before handing it back to France from August to January.

The 200-metre-long, 40-metre-wide island is closed to the public and has no residents, but officials from both countries maintain it in turn. The arrangement, known as a condominium, dates back to the Treaty of the Pyrenees in 1659, which ended nearly a century of war between the two nations. It was on this neutral ground that King Louis XIV of France married Maria Theresa of Spain, the daughter of King Philip IV, a union that sealed peace after years of conflict.

The Treaty of the Pyrenees peace accord, which was negotiated here, established the border (Image: Getty)

More royal meetings followed in the 18th century, earning the island its nickname: “The island of marriages”.

Since the Franco-Spanish boundary line follows the flow of the Bidasoa river's main course - located on the northern shore of the islet - the whole territory of Pheasant Island is actually an enclave within Spain's borders.

Despite its name, no pheasants have ever lived on the island. Locally, it is known as "Isla de los Faisanes" in Spanish, "Île des Faisans" in French and "Konpantzia" in Basque.

Access is strictly forbidden, except on rare heritage open days (Image: Getty)

The island can sometimes be reached on foot from the Spanish side at low tide. However, access is strictly forbidden, except on rare heritage open days. Other than that, employees of the municipal government of Irun or Hendaye may access the island once every six months for cleaning and gardening and members of the Naval Commands of San Sebastián (Spain) and Bayonne (France) -  responsible for monitoring the island - land on it every five days.

Today, the island faces erosion  issues, with its size and shape having changed somewhat over the centuries. At times, there was concern that it might shrink significantly or even vanish due to river currents. To counter this, both nations have cooperated on protective measures to stabilise the land area. Efforts include reinforcing embankments and monitoring changes.

There are currently eight condominiums in the world, including Lake Constance, the tridominium between Austria, Germany, and Switzerland, the Brčko District shared by Bosnia and Herzegovina, and the disputed territory of the Republika Srpska.