The Great Barrier Reef is a series of coral reefs extending along the East of Queensland, Australia, for over 1,300 miles from the North side of Torres Strait to Cape Sandy, at a distance of from 10 to 150 miles from the coast, but in general from 15 to 20 miles. Its foundation represents the old coast line of Australia. The area has been computed at some 100,000 square miles. Gaps are most numerous in the southern portion, and are due chiefly to the fresh water of the rivers, which is unfavorable to the growth of the coral polyps.