What’s The Difference Between a Cay and an Island?

Wondering if there's a difference between an island and a cay? Wondering what the difference is? Here's what you need to know about cays and islands.


Almost everyone in the world knows what an island is. The Bahamas as a country is comprised of a series of islands, but when people begin researching for their trips here they see that many of the smaller islands are referred to as “cays”. It leads them to wonder if there are differences between the two, and if so what are they?



An island is simply any landmass that’s completely surrounded by water. Islands are formed in one of two ways. The first way is by volcanic action, which is how Hawaii, Japan, and the Philippines were created. A continental plate floating on top of the Earth’s mantle can also form islands. Greenland and Australia are both classified as continental islands.



Cays actually are technically different than islands because rather than being formed by volcanic action or continental plates, cays are low-elevation landmasses formed on top of coral reefs. The ocean transports loose sediment across a reef where it accumulates and builds up. Wildlife helps fertilize the sediment making it possible for vegetation to grow and thrive.


The Differences

Often islands and cays are indistinguishable to the eye. The difference between the two comes down to the formation. Although there are technical differences between the two, the two terms are commonly used interchangeably. It isn’t inaccurate to call a cay an island since it does meet the criteria of being surrounded by water on all sides.


Remember geometry from school? The concept that every square is a rectangle but not every rectangle is a square works here.

Every cay is an island but not every island is a cay.



To the average person, understanding the difference between an island and a cay isn’t important to enjoying their vacation. But if you’re curious now you know. When you go off exploring Exuma though chances are you’ll be mostly standing on cays.


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