Reef trending parallel to, but separated by a lagoon from, a shore. The reef-building organisms build up the structure to approximately the low tide level. One of the finest examples is the Great Barrier Reef which lies off the north-eastern coast of Australia: it extends for about 1900 km and is 30–160 km in width.
Geography
A coral reef, stretching along a line parallel with the coastline but separated from it by a wide, deep lagoon, the most famous of which is the Great Barrier Reef off north-west Australia (see D. Hopley et al. 2007).