The Marine Environment in Thailand

Discovering the underwater world

The Marine Environment

Throughout history, humans have submerged themselves in the marine environment to observe it directly for scientific exploration, profit, or adventure.


As early as 4,500 B.C., brave and skillful divers reached depths of 30 meters (100 feet) on one breath of air to retrieve red coral and mother-of-pearl shells. Later, diving bells (bell-shaped structures full of trapped air) were lowered into the sea to provide passengers or underwater divers with an air supply. In 360 B.C, Aristotle, in his Problematum, recorded the use by Greek divers of kettles full of air lowered into the sea.


However, technology to move around freely while breathing underwater was not developed until 1943, when Jacques-Yves Cousteau and Émile Gagnan invented the fully automatic, compressed-air Aqualung. The equipment was later dubbed ‘SCUBA’, an acronym for Self-Contained Underwater Breathing Apparatus, and it is used by millions of recreational divers today.

By using SCUBA, divers can experience the ocean first hand, leading to a fuller appreciation of the wonder and beauty of the marine environment. Those who venture underwater must contend with many obstacles inherent in ocean diving, such as low temperatures, darkness, and the effects of greatly increased pressure.

To combat low temperatures, specially designed clothing is worn. Waterproof, high-intensity diving lights are used to combat darkness. To combat the deleterious effects of pressure, depth and duration of dives must be limited.

Recreational Diving a result, most scuba divers rarely venture below a depth of 30 meters (100 feet) where the pressure is three times that at the surface and they stay there less than 30 minutes.

It is relatively dangerous for humans to enter the marine environment because our bodies are adapted to living in the relatively low pressure of the atmosphere.

In water, pressure increases rapidly with depth, to which anyone who has been to the bottom of the deep end of a swimming pool can attest. The increased pressure at depth in the ocean can cause problems for divers.

Limiting Factors – S.A.F.E Dive – ‘Slowly Ascend from Every Dive’

For instance, higher pressure causes more nitrogen to be dissolved in a diver’s body and may cause a disorienting condition known as nitrogen narcosis or rapture of the deep. Further, if a diver surfaces too rapidly, expanding gases within the body can catastrophically rupture cell membranes (a condition called barotrauma).

In addition, when divers return to the surface, they may experience decompression sickness, which is also called caisson disease, or ‘the bends’.

The bends affects divers who ascend to the lower pressure at the surface too rapidly, causing nitrogen bubbles to form in the bloodstream and other tissues (analogous to the bubbles that form in a carbonated beverage when the container is opened).

Various symptoms can result, from nosebleed and joint pain (which causes divers to stoop over, hence the term the bends) to permanent neurological injury and even fatal paralysis.

To avoid it, divers must ascend slowly, allowing time for excess dissolved nitrogen to be eliminated from the blood via the lungs.

Deeper Into Diving

Despite these risks, divers venture to greater and greater depths in the ocean. In 1962, Hannes Keller and Peter Small made an open-ocean dive from a diving bell to a then record-breaking depth of 304 meters (1,000 feet). Although they used a special gas mixture, Peter Small died once they returned to the surface.

Presently, the record ocean dive is 534 meters (1,750 feet), but researchers who study the physiology of deep divers have simulated a dive to 701 meters (2,300 feet) in a pressure chamber using a special mix of oxygen, hydrogen, and helium gases. Researchers believe that humans will eventually be able to stay underwater for extended periods of time at depths below 600 meters (1,970 feet).

In technical recreational diving the world record Guinness is hold by Ahmed, a 41-year-old Egyptian, has broken the record for the deepest SCUBA dive, plunging an astonishing 332.35 m (1,090 ft 4.5 in) in the Red Sea off the coast of Dahab, Egypt.

Ahmed’s amazing dive broke the previous mark of 318.25 m (1,044 ft) by South African Nuno Gomes in 2005, also off the coast of Dahab.

In order to make the record dive, numerous precautions and preparations needed to be taken to ensure Ahmed’s safety and success. The special forces officer in the Egyptian Army has spent 17 years as a diving instructor and used the last four training for the attempt.

Author: Guillermo Sanchez (PADI IDCS #288160)

Crystal Dive Koh Tao

7/1 Moo 2
Tambon Ko Tao
Koh Tao
Surat Thani


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