Tuesday, April 21, 2009

The Great Blue Hole of Belize Barrier Reef

The Belize Barrier Reef is the longest barrier reef in the Western Hemisphere and the second longest in the world. It is a series of coral reefs straddling the coast of Belize, roughly 300 meters offshore in the north and 40 kilometers in the south within the country limits. The Belize Barrier Reef is a 300 kilometers long section of the 900 kilometers long Mesoamerican Barrier Reef System, which is continuous from Cancún on the northeast tip of the Yucatán Peninsula through the Riviera Maya up to offshore Guatemala, making it the second largest coral reef system in the world after the Great Barrier Reef in Australia, popular for scuba diving and snorkeling. It is Belize's top tourist destination, attracting almost half of its 260,000 visitors, and vital to its fishing industry.

The Great Blue Hole

The three Belize atoll reefs are formed on two tiers of submarine ridges: Turneffe and Glover's on one ridge and Lighthouse on a separate ridge farther to the east. This accounts for their similar outlines and NE-SW orientations. Deep marine trenches separate the two ridges.

Inside the reef the water is shallow, with a blue tinge; outside the reef the water is deep and from the air shows a dark royal blue. On very clear days the reef appears as a narrow yellow line dividing the two shades of blue. Only near Ambergris Caye does the reef run so close to a well-populated caye. Here it is an almost so!id wall of magnificent coral formation broken only by narrow channels called "quebradas". Here an observant diver can be kept entertained for hours on end by the unending variety, shapes and colours ofthe tropical coral.

But the reef is more than just a decorative sideshow. Without it the island would not exist for it serves as a natural break-water protecting the beach from erosion by the waves, and sheltering the caye and its inhabitants. The remarkably clear and shallow water inside the reef allows excellent viewing of the fabulous marine life of the area. Rainbow tinged tropical fish, delicate sea fans and majestic coral gardens abound. Outside the reef, the seabed drops sharply in a series of plateau to depths of thousands of feet. Out here in the blue are found the gamefish - mackerel, kingfish, wahoo, tuna, sailfish and marlin.



The Great Blue Hole
The Great Blue Hole is a large underwater sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 100 kilometres (62 mi) from the mainland and Belize City. The hole is circular in shape, over 300 metres (984 ft) across and 125 metres (410 ft) deep. It was formed as a limestone cave system during the last glacial period when sea levels were much lower. As the ocean began to rise again, the caves flooded, and the roof collapsed. Believed to be the world’s largest feature of its kind, the Great Blue Hole is part of the larger Belize Barrier Reef Reserve System, a World Heritage site of the United Nations Educational, Scientific and Cultural Organization (UNESCO).

This is a popular spot amongst recreational scuba divers, who are lured by the opportunity to dive in crystal clear water and meet several species of fish, including giant groupers, nurse sharks and several types of reef sharks such as the Caribbean reef shark and the Blacktip shark. Other species of sharks, like the bull shark and hammerheads, have been reported there, but are not regular sightings. Usually, dive trips to the Great Blue Hole are full-day trips, which include one dive in the Blue Hole and two further dives in nearby reefs.

The temperature in the Blue Hole at 130ft is about 76F with hardly any change throughout the year at that depth. For all the practical purposes the over 400-foot depth makes the Blue Hole a bottomless pit. The walls are sheer from the surface until a depth of approximately 110 feet where you will begin to encounter stalactite formtions which actually angle back, allowing you to dive underneath monstrous overhangs.



Hovering amongst the stalactites, you can't help but feel humbled by the knowledge that the massive formation before you once stood high and dry above the surface of the sea eons ago. The feeling is enhanced by the dizzying effect of nitrogen breathed at depths. The water is motionless and the visibility often approaches 200 feet as you break a very noticeable thermocline.

Sources: bushtracks.com, wikipedia.org, ambergriscaye.com, ambergriscaye.com, wondersofbelize.com, latimes.com

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