What is a Cay? Why are they special?

A Cay, pronounced as "key" is defined as a low bank or reef of coral, rock, or sand. More commonly, it is a sand island located on the surface of a coral reef.  They usually occur in tropical areas, including the Great Barrier Reef, where they are spotted throughout the marine park. The Reef is home to several cays, including Michaelmas Cay, Green Island and Lady Elliot, which are the most well known.

Cays are formed when ocean currents deposit sand and other sediments on a reef, where it will build up, creating a sand island, seemingly in the middle of no where. The cays are surrounded by reefs, and often draw tourists in for great snorkelling on fringing reefs. There are several cays that have resorts on them, making them a great escape from the mainland tourist attractions. 

Size, shape and lifetime of cays often depend on many outside factors, such as tide, weather patterns, currents, and the shape of the underlying reef. Of the current cays in the reef, it is said that some are forming, while others are getting smaller, depending on those outside factors. Green Island is said to be four times smaller than it used to be, with much of the island washed away by the tides, according to ancient Aboriginal lore. It is currently around 15 hectares in size.

These unique land formations are a beautiful part of the Great Barrier Reef ecosystem and contribute to the overall beauty and diversity of the world's largest reef. Don't be fooled, just because they are primarily made of sand does not mean they cannot sustain vegetation, wildlife, buildings and resorts. There are a few cays in the Great Barrier Reef Marine Park that are not only ideal for visiting, but also for staying on for a unique vacation.