Serranilla Bank

Serranilla Bank (Isla Serranilla, Banco Serranilla and Placer de la Serranilla) is a partially submerged reef, with small uninhabited islets, in the western Caribbean Sea. It is situated about 350 km northeast of Punta Gorda, Nicaragua, and roughly 280 km southwest of Jamaica. The closest neighbouring land feature is Bajo Nuevo Bank, located 110 km to the east.

Serranilla Bank was first shown on Spanish maps in 1510. It is administered by Colombia as part of the department of San Andrés and Providencia. The reef is subject to a sovereignty dispute involving Colombia and the United States. A previous claim by Honduras was resolved in favor of Colombia when the two countries approved a treaty establishing their maritime boundaries. Jamaica's claim was resolved when it established a joint regime area with overlapping maritime boundaries in 1993, but acknowledging Colombian control of Serranilla and Bajo Nuevo banks. In 2012, in regards to Nicaraguan claims to the islands, the International Court of Justice (ICJ) upheld Colombia's sovereignty over the bank, although the judgment does not analyze or mention the U.S. claim over the reef.

Geography
Serranilla Bank is a former atoll, now a mostly submerged carbonate platform consisting of shallow reef environments. It is about 40 km in length and 32 km in width, covering an area of over 1200 km2, almost entirely under water. Three small cays and two rocks emerge above the water to form the bank's islands. These are West Breaker, Middle Cay, East Cay, Beacon Cay and Northeast Breaker. They are largely barren, with sparse vegetation of bushes and some trees. Many shipwrecks are located in its vicinity. The bank lacks coral reefs and has minimal sediment cover. Accretion of the bank is not keeping up with sea level rise. The southeastern portion is covered mainly by hardgrounds, while the rest of the bank is mostly covered by thin Halimeda sediments.

Beacon Cay is the largest islet in the Bank. It is overbuilt with small military facilities, which house a small rotating garrison of Colombian naval personnel. There is a lighthouse on a coral ledge in the southwest approach to the bank. It is a 33 m tall skeletal tower built atop a 3-storey crew residence. The lamp emits a focal plane beam of light as two white flashes every 20 seconds. The current lighthouse was first erected in 1982, and was reconstructed in May 2008 by the Colombian Ministry of Defence. It is currently maintained by the Colombian Navy, and overseen by the state's Maritime Authority.

History
The Serranilla Bank was first shown on Spanish maps in 1510 as Placer de la Serranilla. It was mentioned by Louis-Michel Aury whose ship was shipwrecked on it in 1820. In later history it has been the subject of conflicting claims by a number of sovereign states; in most cases, the dispute stems from attempts by a state to expand its exclusive economic zone over the surrounding seas.

Between 1982 and 1986, Colombia maintained a formal agreement with Jamaica which granted regulated fishing rights to Jamaican vessels within the territorial waters of Serranilla Bank and nearby Bajo Nuevo Bank. In November 1993, the two states agreed upon a maritime delimitation treaty establishing a "Joint Regime Area" to cooperatively manage and exploit living and non-living resources in designated waters between the two banks. However, the territorial waters immediately surrounding the cays themselves were excluded from the zone of joint-control, as Colombia considers these areas to be part of her coastal waters. The agreement came into force in March 1994.

Nicaragua formerly claimed all the islands on its continental shelf, covering an area of over 50,000 km2 in the Caribbean Sea, including the Serranilla Bank and all islands associated with the San Andrés and Providencia archipelagoes. It had persistently pursued this claim against Colombia in the International Court of Justice (ICJ), filing cases in both 2001 and 2007. Nicaragua formally accepted the ICJ's 2012 ruling of Colombian sovereignty in a 2014 constitutional amendment.

The United States' claim was made in 1879 and 1880 under the Guano Islands Act by James W. Jennett. Most claims made by the U.S. over the guano islands in this region were officially renounced in a treaty with Colombia, dated September 1972. But whether or not Serranilla Bank was included in the agreement is disputed—there is no specific mention of the feature in the treaty and, as per Article 7 of the said treaty, only matters specifically mentioned in the document are subject to it. The U.S. considers the reef to be an insular area.

Honduras claimed Serranilla Bank as part of its national territory in Article 10 of its Constitution. In 1986, it agreed upon a maritime boundary demarcation with Colombia that excluded Honduras of any control over the bank or its surrounding waters. The ratification of this boundary on 20 December 1999 proved to be controversial within Honduras, as it ensured that the state implicitly recognised Colombia's sovereignty over the claimed territory. At that time, Nicaragua disputed Honduras' legal right to hand over these areas before the ICJ. Despite the agreement with Colombia, however, the Honduran government has yet to officially renounce the claim in the Constitution.

Notable fauna
In 1952, Serranilla Bank was the site of the last sighting of the now extinct Caribbean monk seal.