Great Blue Hole

The Great Blue Hole, near Belize City, Belize
Lighthouse Reef as seen from space. The Great Blue Hole is near the center of the photograph.

The Great Blue Hole is a large submarine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 70 km (43 mi) from the mainland and Belize City. The hole is circular in shape, over 300 m (984 ft) across and 124 m (407 ft) deep.[1] It was formed during several episodes of quaternary glaciation when sea levels were much lower. Analysis of stalactites found in Great Blue Hole shows that formation took place 153,000; 66,000; 60,000; and 15,000 years ago.[2] As the ocean began to rise again, the cave was flooded.[3] The Great Blue Hole is a part of the larger Belize Barrier Reef Reserve System, a World Heritage Site of the United Nations Educational, Scientific and Cultural Organization (UNESCO).[4]

Exploration and name

This site was made famous by Jacques Cousteau, who declared it one of the top ten scuba diving sites in the world. In 1971, he brought his ship, the Calypso, to the hole to chart its depths.[5] Investigations by this expedition confirmed the hole's origin as typical karst limestone formations, formed before rises in sea level in at least four stages, leaving ledges at depths of 21 m (69 ft), 49 m (161 ft), and 91 m (299 ft). Stalactites were retrieved from submerged caves, confirming their previous formation above sea level. Some of these stalactites were also off-vertical by 5˚[1] in a consistent orientation, indicating that there had also been some past geological shift and tilting of the underlying plateau, followed by a long period in the current plane.

Initial measured depth of Great Blue Hole was 125 m (410 ft) which is the most often cited depth up to this day. An expedition by the Cambrian Foundation in 1997 measured the hole's depth as 124 m (407 ft)[1][2] at its deepest point. This difference in measurement can be explained by ongoing sedimentation or by imprecision in measurements. The expedition's goal was to collect core samples from the Blue Hole's floor and document the cave system.[6] To accomplish these tasks, all of the divers had to be certified in cave diving and mixed gases.[6]

The actual name of “The Great Blue Hole” was created by British diver and author Ned Middleton after having lived in the country for six months. So impressed with this natural feature, he reasoned in his book “Ten Years Underwater” (Immel Publishing 1988, ISBN 0907151434) that if Australia could have ‘The Great Barrier Reef’ then Belize could equally have ‘The Great Blue Hole’ – thus setting this feature apart from similar, albeit smaller structures. This was later reinforced by his second book “Diving Belize” (AquaQuest publishing, USA 1994 ISBN 1881652017).

Tourism

This is a popular spot among recreational scuba divers who are lured by the opportunity to dive in sometimes crystal-clear water and meet several species of fish, including Midnight Parrotfish, Caribbean reef shark, and other juvenile fish species. Other species of sharks, such as the bull shark and hammerheads, have been reported there, but are not regularly sighted. Usually, day trips to the Great Blue Hole are full-day trips from the coastal tourist communities in Belize.

On-shore caves of similar formation, as large collapsed sinkholes, are well known in Belize and in the Yucatán Peninsula, where they are known as cenotes. Unlike the mainland cenotes which often link to underwater cave systems, there is little evidence of horizontal development in the Blue Hole.

In 2012, Discovery Channel ranked the Great Blue Hole as number one on its list of "The 10 Most Amazing Places on Earth".[7]

See also

References

  1. ↑ 1.0 1.1 1.2 The Great Blue Hole of Lighthouse Reef Atoll, Belize, Central America: Deep Technical Diving to Collect Sea-Level Records. Transactions of the Fifteenth Caribbean Geological Conference.
  2. ↑ 2.0 2.1 "Great Blue Hole". Wondermondo.
  3. ↑ "Belize Blue Hole reef". NASA.
  4. ↑ "World Heritage Nomination - IUCN Summary Belize Barrier Reef Reserve System (Belize)". IUCN/WCMC.
  5. ↑ Jacques-Yves Cousteau (1973). Galapagos - Titicaca - The Blue Holes. London: Cassell.
  6. ↑ 6.0 6.1 Tysall, Terrance N (1999). "The Belize Blue Hole Exploration Project.". In: Hamilton RW, Pence DF, Kesling DE, eds. Assessment and Feasibility of Technical Diving Operations for Scientific Exploration. (American Academy of Underwater Sciences). Retrieved 2011-01-08.
  7. ↑ Robert Lamb; Amanda Arnold (2012). "The 10 Most Amazing Places on Earth". Discovery Channel. Archived from the original on 2012-11-09. Retrieved 2013-09-12.

External links

Great Blue Hole website

Coordinates: 17°18′55″N 87°32′4″W / 17.31528°N 87.53444°W