Catherine Le Nevez –
There’s a reason that it’s called the Great Barrier Reef.
With a surface area larger than the British Isles, the most extensive reef system in the world is 2,000km long: the only living structure visible from the International Space Station.
It’s made up of more than 3,000 separate fringing reefs that lie between Australia’s Queensland coast and the edge of the continental shelf.
All exist thanks to colonies of tiny polyps, the “architects” of the reef, whose outer skeletons form intricate multicoloured coral metropolises.
Monty Halls’ recent BBC series showcased this Unesco World Heritage-listed treasure, which is home to not only the world’s greatest concentration of coral (400 types of hard coral and 300 types of soft coral) and 1,500 or so species of glittering fish, but also 4,000 breeds of molluscs; 500 types of seaweed; 1,500 varieties of sponges; 200 bird species; and more than 30 marine mammal species including humpback, minke, killer and pilot whales.
The reef stretches from just south of the tropic of Capricorn to north of Cape York, and incorporates about 900 coral islands.
For a close-up of the kaleidoscope of corals and marine life teeming below the surface, diving and snorkelling offer a truly hypnotic, outer space-like experience in the warm waters (often as shallow as a swimming pool).
The reef lies 16km to 160km off the Queensland shore.
Day cruises generally incorporate about three hours of underwater exploration and include snorkelling gear, with many day trips offering diving as an optional add-on for certified divers for about A$250 (£167) for two dives including gear.
Some also offer an introductory dive – a controlled scuba dive with no certification or experience necessary – from around A$245 (£163), with additional dives about A$40 (£27).