A cay (/ˈkiː/ or /ˈkeɪ/), also spelled caye or key, is a small, low-elevation, sandy island on the surface of a coral reef. Cays occur in tropical environments throughout the Pacific, Atlantic and Indian Oceans (including in the Caribbean and on the Great Barrier Reef and Belize Barrier Reef).


The 1492 indigenous people of the Bahamas were called "Lucayan", an Anglicization of the Spanish Lucayos, derived in turn from the Taíno Lukku-Cairi (which the people used for themselves), meaning "people of the islands". The Taíno word for "island", cairi, became cayo in Spanish and "cay" /ˈkiː/ in English (spelled "key" in American English, "caye" in Belizean English).[1]

Formation and composition

Cay sand
Cay sand under an optical microscope

A cay forms when ocean currents transport loose sediment across the surface of a reef to a depositional node, where the current slows or converges with another current, releasing its sediment load. Gradually, layers of deposited sediment build up on the reef surface.[2][3] Such nodes occur in windward or leeward areas of reef where surfaces sometimes occur around an emergent outcrop of old reef or beach rock.

The island resulting from sediment accumulation is made up almost entirely of biogenic sediment – the skeletal remains of plants and animals – from the surrounding reef ecosystems.[4] If the accumulated sediments are predominantly sand, then the island is called a cay; if they are predominantly gravel, the island is called a motu.

Cay sediments are largely composed of calcium carbonate (CaCO3), primarily of aragonite, calcite, and high magnesium calcite. They are produced by myriad plants (e.g., coralline algae, species of the green algae Halimeda) and animals (e.g., coral, molluscs, foraminifera). Small amounts of silicate sediment are also contributed by sponges and other creatures.[5][6][7][8] Over time, soil and vegetation may develop on a cay surface, assisted by the deposition of sea bird guano.

Development and stability

A range of physical, biological and chemical influences determines the ongoing development or erosion of cay environments. These influences include: the extent of reef surface sand accumulations, changes in ocean waves, currents, tides, sea levels and weather conditions, the shape of the underlying reef, the types and abundance of carbonate producing biota and other organisms such as binders, bioeroders and bioturbators (creatures that bind, erode, and mix sediments) living in surrounding reef ecosystems.[9][10]

Significant changes in cays and their surrounding ecosystems can result from natural phenomena such as severe El Niño–Southern Oscillation (ENSO) cycles. Also, tropical cyclones can help build or destroy these islands.[11][12]

There is much debate and concern over the future stability of cays in the face of growing human populations and pressures on reef ecosystems, and predicted climate changes and sea level rise.[13][14] There is also debate around whether these islands are relict features that effectively stopped expanding two thousand years ago during the late Holocene or, as recent research suggests, they are still growing, with significant new additions of reef sediments.[15]

Understanding the potential for change in the sediment sources and supply of cay beaches with environmental change is an important key to predicting their present and future stability. Despite, or perhaps because of all the debate around the future of cays, there is consensus that these island environments are very complex and somewhat fragile.


Examples of cays include:

See also


  1. ^ Albury:5, 13–14
  2. ^ Hopley, D. (1981). "Sediment movement around a coral cay, Great Barrier Reef, Australia". Pacific Geology. 15: 17–36.
  3. ^ Gourlay, M.R. (1988) "Coral cays: products of wave action and geological processes in a biogenic environment" pp. 497–502. In Choat, J.H. et al. (eds.) Proceedings of the 6th International Coral Reef Symposium: Vol. 2: Contributed Papers. Townsville, Australia.
  4. ^ a b Hopley, D. (1982) The Geomorphology of the Great Barrier Reef – Quaternary Development of Coral Reefs. Wiley-Interscience Publication, John Wiley and Sons Ltd., New York, ISBN 0471045624.
  5. ^ Chave, K. (1964) "Skeletal Durability and Preservation". In: J. Imbrie and N. Newell (Eds.), Approaches to Palaeoecology. John Wiley and Sons Inc., Sydney.
  6. ^ Folk, R.; Robles, P. (1964). "Carbonate sands of Isla Perez, Alacran Reef Complex, Yucatan". Journal of Geology. 72 (3): 255–292. doi:10.1086/626986. JSTOR 30075161.
  7. ^ Scoffin, T.P. (1987) Introduction to Carbonate Sediments and Rocks. Blackwell, Glasgow, ISBN 0216917891.
  8. ^ Yamano, H., Miyajima, T. and Koike, I. (2000). "Importance of foraminifera for the formation and maintenance of a coral sand cay: Green Island, Australia". Coral Reefs. 19: 51–58. doi:10.1007/s003380050226.CS1 maint: uses authors parameter (link)
  9. ^ Harney, J.N.; Fletcher, C.H. (2003). "A budget of carbonate framework and sediment production, Kailua Bay, Oahu, Hawaii" (PDF). Journal of Sedimentary Research. 73 (6): 856–868. doi:10.1306/051503730856.
  10. ^ Hart, D.E.; Kench, P.S. (2006). "Carbonate production of an emergent reef platform, Warraber Island, Torres Strait, Australia" (PDF). Coral Reefs. 26: 53–68. doi:10.1007/s00338-006-0168-8. hdl:10092/312.
  11. ^ Scoffin, T.P. (1993). "The geological effects of hurricanes on coral reefs and the interpretation of storm deposits". Coral Reefs. 12 (3–4): 203–221. doi:10.1007/BF00334480.
  12. ^ Woodroffe, C.D. (2003) Coasts: Form, Process and Evolution. Cambridge University Press, Cambridge, ISBN 0521011833.
  13. ^ Kench, P.S.; Cowell, P. (2002). "Erosion of low-lying reef islands". Tiempo Climate Newswatch. 46: 6–12. Archived from the original on 2013-05-10.
  14. ^ Hart, D.E. (2003) "The importance of Sea-Level in an Inter-Tidal Reef Platform System, Warraber Island, Torres Strait". Proceedings of the 22nd Biennial New Zealand Geographical Society Conference, Auckland, 2003. pp 77–81.
  15. ^ Woodroffe, C.D., Samosorn, B., Hua, Q. and Hart, D. E. (2007). "Incremental accretion of a sandy reef island over the past 3000 years indicated by component-specific radiocarbon dating". Geophysical Research Letters. 34 (3). CiteSeerX doi:10.1029/2006GL028875.CS1 maint: uses authors parameter (link)
  16. ^ McLean, R.; Stoddart, D. (1978). "Reef island sediments of the northern Great Barrier Reef". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 291 (1378): 101. doi:10.1098/rsta.1978.0093. JSTOR 75221.
  17. ^ Woodroffe, C.D., Kennedy, D.M., Hopley, D., Rasmussen, C.E. and Smithers, S.G. (2000). "Holocene reef growth in Torres Strait". Marine Geology. 170 (3–4): 331–346. doi:10.1016/S0025-3227(00)00094-3.CS1 maint: uses authors parameter (link)
Abaco Islands

The Abaco Islands lie in the northern Bahamas, 180 miles off the South Florida coast. They comprise the main islands of Great Abaco and Little Abaco, along with smaller barrier cays. The northernmost are Walker's Cay, and its sister island Grand Cay. To the south, the next inhabited islands are Spanish Cay and Green Turtle Cay, with its settlement of New Plymouth, Great Guana Cay, private Scotland Cay, Man-O-War Cay, and Elbow Cay, with its settlement of Hope Town. Southernmost are Tilloo Cay and Lubbers Quarters. Another of note off Abaco's western shore is onetime Gorda Cay, now a Disney Island and cruise ship stop and renamed Castaway Cay. Also in the vicinity is Moore's Island. On the Big Island of Abaco is Marsh Harbour, the Abacos' commercial hub and the Bahamas' third largest city, plus the resort area of Treasure Cay. Both have airports. A few mainland settlements of significance are Coopers Town and Fox Town in the north and Cherokee and Sandy Point in the south. Administratively, the Abaco Islands constitute seven of the 31 Local Government Districts of the Bahamas: Grand Cay, North Abaco, Green Turtle Cay, Central Abaco, South Abaco, Moore's Island, and Hope Town.

Berry Islands

The Berry Islands are a chain of islands and a district of the Bahamas, covering about thirty square miles (78 km2) of the northwestern part of the Out Islands.

The Berry Islands consist of about thirty islands and over one hundred small islands or cays, often referred to as "The Fish Bowl of the Bahamas." They have a population of 807 (2010 census), most of whom are on Great Harbour Cay. The islands were settled in 1836 by Governor William Colebrooke with a group of freed slaves.

Castaway Cay

Castaway Cay is a private island in the Bahamas which serves as an exclusive port for the Disney Cruise Line ships. It is located near Great Abaco Island and was formerly known as Gorda Cay. In 1997, The Walt Disney Company purchased a 99-year land lease (through 2096) for the cay from the Bahamian government, giving the company substantial control over the island.Castaway Cay was the first private island in the cruise industry where the ship docks on the island, eliminating the need for guests to be tendered to land.The island is still largely undeveloped as only 55 of the 1,000 acres (4.0 km2) are being used. Castaway Cay now has approximately 140 Disney Cruise Line permanent residents who keep the island running daily; the numbers fluctuate between the busy and off seasons.


Caycay (pronounced [kaɪkaɪ]) is a Filipino crunchy layered cookie coated in syrup (latik) or honey and rolled in coarsely ground toasted peanuts. It originates from the islands of Bohol and Cebu and is a common specialty in the southern Visayas islands and Mindanao. The name comes from the verb kaykay which means "to dig up" in the Cebuano language, in reference to the step of coating the cookies in ground peanuts. Some versions coat the cookies in sesame seeds instead of peanuts.

Coral Sea Islands

The Coral Sea Islands Territory is an external territory of Australia which comprises a group of small and mostly uninhabited tropical islands and reefs in the Coral Sea, northeast of Queensland, Australia. The only inhabited island is Willis Island. The territory covers 780,000 km2 (301,160 sq mi), most of which is ocean, extending east and south from the outer edge of the Great Barrier Reef and includes Heralds Beacon Island, Osprey Reef, the Willis Group and fifteen other reef/island groups. Cato Island is the highest point in the Territory.


Cymbopogon, variously known as lemongrass, barbed wire grass, silky heads, Cochin grass or Malabar grass or oily heads , is a genus of Asian, African, Australian, and tropical island plants in the grass family.

Some species (particularly Cymbopogon citratus) are commonly cultivated as culinary and medicinal herbs because of their scent, resembling that of lemons (Citrus limon). Other common names include barbed wire grass, silky heads, citronella grass, and fever grass, amongst many others.

The name cymbopogon derives from the Greek words kymbe (κύμβη, 'boat') and pogon (πώγων, 'beard') "which mean [that] in most species, the hairy spikelets project from boat-shaped spathes."


Exuma is a district of the Bahamas, consisting of over 365 islands, also called cays.

The largest of the cays is Great Exuma, which is 37 mi (60 km) in length and joined to another island, Little Exuma, by a small bridge. The capital and largest town in the district is George Town (population 1,437). It was founded 1793 and located on Great Exuma. Near the town, but on Little Exuma, the Tropic of Cancer runs across Pelican Beach lending it another name: Tropic of Cancer Beach. Its white sand and turquoise waters make it a world-famous destination. The entire island chain is 130 mi (209 km) long and 72 sq mi (187 km²) in area. Great Exuma island has an area of 61 sq mi (158 km²) while Little Exuma has an area of 11 sq mi (29 km²).Between 2000 and 2010, the population of Exuma more than doubled, reflecting the construction of large and small resort properties and the related direct air traffic to Great Exuma from locations as distant as Toronto, Ontario, Canada. The population in 2010 was 6,928.

List of Caribbean islands

A list of islands in the Caribbean Sea, in alphabetical order by country of ownership and/or those with full independence and autonomy.

List of Torres Strait Islands

The Torres Strait Islands are a group of at least 274 small islands in the Torres Strait. This is an incomplete list of islands in the Torres Strait.

List of islands of The Bahamas

The following is an alphabetical list of the islands of the Commonwealth of the Bahamas.

Michaelmas and Upolu Cays National Park

Michaelmas and Upolu Cays is a national park in Queensland, Australia, 1,409 km (876 mi) northwest of Brisbane and 33 km (21 mi) east of Cairns. It comprises two small cays on Michaelmas Reef, which forms the north-eastern section of the Arlington reef complex, within the Great Barrier Reef.

Mỏ Cày Nam District

Mỏ Cày Nam is a rural district (huyện) of Bến Tre Province in the Mekong Delta of Vietnam. The district is established on March 2009.

Mỏ Cày Nam is bordering with Giồng Trôm District on east, Trà Vinh Province on the west, Mỏ Cày Bắc and Giồng Trôm districts on the north and northeast; Thạnh Phú District and Trà Vinh Province on the south and southwest.

Mỏ Cày Nam has a population of 186,474 and covers an area of 219.9 km2.

This district is subdivided into 1 township (thị trấn) and 16 communes (xã).

Township: Mỏ Cày (district seat)

Communes: Định Thuỷ, Phước Hiệp, An Thạnh, Đa Phước Hội, Thành Thới B, Bình Khánh Đông, Bình Khánh Tây, An Định, An Thới, Thành Thới A, Hương Mỹ, Cẩm Sơn, Ngãi Đăng, Minh Đức, Tân Trung, Tân Hội.

Paradise Cay, California

Paradise Cay, also known as County Service Area No. 29, is an unincorporated enclave, surrounded by the town of Tiburon in Marin County, California, located 2 miles (3 km) south of Point San Quentin at an elevation of 23 feet (7 m). The waterfront community lies at the foot of the Tiburon Peninsula south of Corte Madera Creek along San Francisco Bay. The community is in ZIP code 94920 and area code 415.


Samurçay (also, Samurçay) is a village in the municipality of Nabran in the Khachmaz Rayon of Azerbaijan.

Serranilla Bank

Serranilla Bank (Spanish: 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 kilometres (220 mi) northeast of Punta Gorda, Nicaragua, and roughly 280 kilometres (170 mi) southwest of Jamaica. The closest neighbouring land feature is Bajo Nuevo Bank, located 110 kilometres (68 mi) 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, Honduras and the United States. In 2012, in regards to Nicaraguan claims to the islands, the International Court of Justice (ICJ) upheld Colombia's sovereignty over the bank.

Tea in Turkey

Tea (Turkish: çay pronounced [tʃaj]) is popular throughout Turkey and the Turkish diaspora. Turkish tea culture also extends to Northern Cyprus and some countries in the Balkan Peninsula.

The Cay

The Cay is a teen novel written by Theodore Taylor. It was published in 1969.

The Cay took only three weeks to complete. Taylor based the character of the boy in his book on a child who was aboard the Hato, when it was torpedoed, who drifts out to sea on a lifeboat. The novel was published in 1969 and dedicated to Martin Luther King, Jr.

Turks and Caicos Islands

The Turks and Caicos Islands (abbreviated TCI; and ) are a British Overseas Territory consisting of the larger Caicos Islands and smaller Turks Islands, two groups of tropical islands in the Lucayan Archipelago of the Atlantic Ocean and northern West Indies. They are known primarily for tourism and as an offshore financial centre. The resident population was 31,458 as of 2012 of whom 23,769 live on Providenciales in the Caicos Islands; July 2018 estimates put the population at 53,700. It is the third largest of the British overseas territories by population.

The Turks and Caicos Islands lie southeast of Mayaguana in the Bahamas island chain, northeast of Cuba, and north of the island of Hispaniola (Haiti and the Dominican Republic). Cockburn Town, the capital since 1766, is situated on Grand Turk Island about 1,042 kilometres (647 mi) east-southeast of Miami, United States. The islands have a total land area of 430 square kilometres (170 sq mi).The Turks and Caicos Islands were inhabited for centuries by native Amerindian peoples. The first recorded European sighting of the islands occurred in 1512. In the subsequent centuries, the islands were claimed by several European powers, with the British Empire eventually gaining control. For many years the islands were governed indirectly through Bermuda, the Bahamas, and Jamaica. When the Bahamas gained independence in 1973, the islands received their own governor, and have remained a separate autonomous British Overseas Territory since.

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