Cay: low island or reef of coral, sand, etc.

UNESCO: L O S S A R Y

Composed of sedimentary rock (successive layers of coral, shells, sand, and other materials hardened over time), exploring Coral Castle is like wandering among a man's hopes which have been encrusted with disappointment.

BBC: The mystery of Florida��s Coral Castle

Hartman died in 1991, but the do-it-yourself ethos among U.S. expatriates continues to pave the way for better tourism in the Exumas, a chain of 365 Bahamian islands and cays (pronounced "keys"), low reefs of sand or coral.

FORBES: Blackbeard's Beach

We paddle through a channel with a white sand bottom and walls of coral, spotting lobster antennae poking out from crevices.

WSJ: The Ultimate Breathtaking Dive

Later came intensive memorising of the star-compass, a circle of coral pebbles, each pebble a star, laid out in the sand round a palm-frond boat.

ECONOMIST: Mau Piailug