2 THE GREAT BARRIER REEF. 



thirty miles. At one or two isolated points, such as the promontories of Cape Melville and 

 of Cape Direction, the distance is as little as ten or twelve miles. At the northern and the 

 southern extremities of this relatively uniform reef-enclosed channel, the proximity of the 

 outer wall or boundary of the Barrier from the mainland increases considerably. At its 

 northern end it follows a course due north, the trend of the mainland being north-west by 

 north, until, opposite Cape York, Queensland's extreme northern point, there is an intervening 

 distance of over ninety miles. Eastward of Torres Strait the outer wall of the Barrier describes 

 a north and slightly north-easterly course, embracing what is known as the Warrior Reef, 

 Murray and Darnley Islands, and ending in close proximity to the New Guinea coast. South- 

 ward from Cairns and the Trinity Opening, the outer edge of the Barrier for a stretch of nearly 

 I So miles lies off the mainland at a distance varying from forty to sixty miles. From this 

 point it rapidly extends further seawards, its more northerly clearly-defined continuity dis- 

 appears, and it becomes broken up into detached reefs and islets that are ultimately as remote 

 as 150 miles from the Queensland coast-line. 



The area enclosed between the outer edge of the Great Barrier Coral Reef and the Queensland 

 mainland is necessarily of very considerable dimensions, and may be set down, at the lowest approx- 

 imate estimate, at some 80,000 square geographical miles. This extensive area, throughout the 

 greater part of its length, may be said to consist of a perfect archipelago of detached reefs and 

 coral islets, the majority of the former of which are completely submerged, or only partially exposed 

 to view at ordinary low water. Although usually represented as forming, with the exception of 

 certain well-defined passages, a continuous wall throughout its length, the outer edge of the Great 

 Barrier Reef must be more correctly described as consisting of a chain of detached reefs of variable 

 lengths, with innumerable openings, only a few of which offer a secure passage for large-sized 

 vessels. The list of these openings, enumerated and named on the Admiralty charts for the 

 navigation of these waters, beginning with the Great North-East (or Bligh) Entrance in the 

 extreme north, and ending with the wide and most southerly entrance of Curtis Channel, is 

 as follows : — 



LIST OF NAVIGABLE PASSAGES THROUGH THE GREAT BARRIER REEF. 



*i. Bligh, or Great North-East Entrance. 



2. FHnder's Entrance. 



3. Yule Entrance. 



4. Olinda Entrance. 



5. Pandora Entrance. 



6. Raine Island Entrance. 



7. Black Rock Entrance. 



8. Quoin Island Entrance. 



9. Providential Channel (Cook, 1770). 

 lo. Second Three Mile Opening. 



1 1 First Three Mile Opening. 



