Ambergris Cays are a group of small islands within the Turks and Caicos Islands. They are situated to the south of the main chain of the Caicos islands. The largest islands are Big Ambergris Cay and Small Ambergris Cay. It was named for valuable deposits of ambergris, a waxy substance that migrating humpback whales secrete, found on the 8 miles (13 km) of shoreline. The island is approximately four miles long, one mile (1.6 km) wide, and 1,100 acres (4.5 km2) in total. It was uninhabited until 1997, but has a small population today. It has been privately owned since 1811.
In the late 18th and early 19th centuries, Loyalists settled on Ambergris Cay, raised cows, made pottery, and built houses, stables, and cisterns (ruins still exist of each of these).
The island has an exclusive private club called Turks & Caicos Sporting Club at Ambergris Cay, which received awards in 2009 from Caribbean World Magazine. It hosts many outdoor pursuits including bonefishing flats; blue water and deep sea fishing and SCUBA diving with guides.
John Lightbourne was the islands first owner, he purchased it from the Bahamas administration in 1811. Horatio Stubbs of South Caicos purchased the island, the dwelling house, and a female slave in 1826 for the cost of 6,000 bushels of salt.
In 1978 an investment group from the state of Arizona tried to purchase Ambergris Cay, with the goal of building a university on the island. This effort was rejected by the government.
The reefs are home to bonefish, jelly fish, conch and spiny lobster. Reports from local fishermen indicate that green and hawksbill sea turtles nest on the island.
The island is home to the native Turks & Caicos Rock Iguana (Cyclura carinata) which is critically endangered. The San Diego Zoo has been working to capture, relocation, and the subsequent examination of homing abilities to assess the viability of relocation.
In her master's thesis in 2009, Sophie Williams a student of Imperial College London identifies Ambergris Cay as an Important Plant Area. She studied three endemic species in her thesis, all of which were found on the island. The three plants she used are Argythamnia argentea, Limonium bahamense and Encyclia caicensis.