Sponge diving is underwater diving to collect soft natural sponges for human use.
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Sponge diving is underwater diving to collect soft natural sponges for human use.
Most sponges are too rough for general use due to their structural spicules composed of calcium carbonate or silica. But two genera, Hippospongia and Spongia , have soft, entirely fibrous skeletons. These two genera are most commonly used by humans.
It is unknown when exactly the sponge became an article of use. In Ancient Greek writings, Homer and Plato mentioned the sponge as an object used for bathing. Through trading, Europeans used soft sponges for many purposes including padding for helmets, portable drinking utensils and municipal water filters. Until the invention of synthetic sponges, they were used as cleaning tools, applicators for paints and ceramic glazes, and discreet contraceptives. However, by the mid-20th century, over-fishing had brought both the animals and the industry close to extinction. [1]
Many objects with sponge-like textures are now made of substances not derived from poriferans. Synthetic "sponges" include: personal and household cleaning tools, breast implants, [2] and contraceptive sponges. [3]
In Kalymnos, only 18% of the steep volcanic land could be cultivated, so the main occupations were trading, boat building and sponge fishing, which perhaps was the oldest occupation on the island. Diving for sponges brought social and economic development to the island: the freediving method was originally used. Kalymnos was the main centre of sponge production in the Aegean, and sponge diving is still a traditional albeit less common occupation of the Greeks on the island, with related exhibitions, along with other local folklore, and three museums about the occupation.
When sponge diving, the crew went out into the Mediterranean Sea in a small boat, and used a cylindrical box with a glass bottom to search the sea floor for sponges. When one was found, a diver went overboard to get it. Freediving, he was usually naked and carried a 15 kilograms (33 lb) skandalopetra, a rounded stone tied on a rope to the boat, to take him down to the bottom quickly. The diver then cut the sponge loose from the bottom and put it into a net bag. Depth and bottom time depended on the diver's lung capacity. They often went down about 30 metres (100 ft) for up to 5 minutes. [4]
When the Greek sponge divers started using surface supplied standard diving suits (locally called scaphandro) in 1865 the death and injury rate from decompression sickness was extremely high as the procedures for safe decompression were as yet unknown. Some estimates put the death toll at around 10,000 Mediterranean divers in the first 50 years of surface supplied diving. [5]
French Navy physician Alfred Le Roy de Mericourt reported that in 1867, the suppliers of the diving suits reported that out of 24 divers using 12 scaphandros, 10 died during the season. [5] By 1868 the Italian doctor Alphonse Gul observed that three divers would share a suit, and of the thirty divers at Kalymnos, two died and two were paralysed that year. The improvement in fatality rate was ascribed to the reduced daily diving time resulting from sharing the suits. [5]
Freediving, free-diving, free diving, breath-hold diving, or skin diving is a form of underwater diving that relies on breath-holding until resurfacing rather than the use of breathing apparatus such as scuba gear.
Deep diving is underwater diving to a depth beyond the norm accepted by the associated community. In some cases this is a prescribed limit established by an authority, while in others it is associated with a level of certification or training, and it may vary depending on whether the diving is recreational, technical or commercial. Nitrogen narcosis becomes a hazard below 30 metres (98 ft) and hypoxic breathing gas is required below 60 metres (200 ft) to lessen the risk of oxygen toxicity.
Diving activities are the things people do while diving underwater. People may dive for various reasons, both personal and professional. While a newly qualified recreational diver may dive purely for the experience of diving, most divers have some additional reason for being underwater. Recreational diving is purely for enjoyment and has several specialisations and technical disciplines to provide more scope for varied activities for which specialist training can be offered, such as cave diving, wreck diving, ice diving and deep diving. Several underwater sports are available for exercise and competition.
A surface marker buoy, SMB, dive float or simply a blob is a buoy used by scuba divers, at the end of a line from the diver, intended to indicate the diver's position to people at the surface while the diver is underwater. Two kinds are used; one (SMB) is towed for the whole dive, and indicates the position of the dive group throughout the dive, and the other, a delayed surface marker buoy, DSMB or decompression buoy, is deployed towards the end of the dive as a signal to the surface that the divers have started to ascend, and where they are going to surface. Both types can also function as a depth reference for controlling speed of ascent and accurately maintaining depth at decompression stops. Surface marker buoys are also used by freedivers in open water, to indicate the approximate position of the diver when submerged. They may also be used to support a catch bag or fish stringer by underwater hunters and collectors. A DSMB is considered by recreational scuba divers and service providers to be a highly important item of safety equipment, yet its use is not part of the entry level recreational diver training for all training agencies, and there are significant hazards associated with incompetent use.
Recreational diving or sport diving is diving for the purpose of leisure and enjoyment, usually when using scuba equipment. The term "recreational diving" may also be used in contradistinction to "technical diving", a more demanding aspect of recreational diving which requires more training and experience to develop the competence to reliably manage more complex equipment in the more hazardous conditions associated with the disciplines. Breath-hold diving for recreation also fits into the broader scope of the term, but this article covers the commonly used meaning of scuba diving for recreational purposes, where the diver is not constrained from making a direct near-vertical ascent to the surface at any point during the dive, and risk is considered low.
The Blue Hole is a diving location on the southeast Sinai, a few kilometres north of Dahab, Egypt on the coast of the Red Sea.
Pearl hunting, also known as pearling, is the activity of recovering pearls from wild molluscs, usually oysters or mussels, in the sea or freshwater. Pearl hunting was prevalent in the Persian Gulf region and Japan for thousands of years. On the northern and north-western coast of Western Australia pearl diving began in the 1850s, and started in the Torres Strait Islands in the 1860s, where the term also covers diving for nacre or mother of pearl found in what were known as pearl shells.
Scuba Schools International (SSI) is a for-profit organization that teaches the skills involved in scuba diving and freediving, and supports dive businesses and resorts. SSI has over 2,500 authorized dealers, 35 regional centers, and offices all over the world.
Underwater diving, as a human activity, is the practice of descending below the water's surface to interact with the environment. It is also often referred to as diving, an ambiguous term with several possible meanings, depending on context. Immersion in water and exposure to high ambient pressure have physiological effects that limit the depths and duration possible in ambient pressure diving. Humans are not physiologically and anatomically well-adapted to the environmental conditions of diving, and various equipment has been developed to extend the depth and duration of human dives, and allow different types of work to be done.
Skandalopetra diving dates from ancient Greece, when it was used by sponge fishermen, and has been re-discovered in recent years as a freediving discipline. It was in this discipline that the first world record in freediving was registered, when the Greek sponge fisherman Stathis Chantzis dived to a depth of 83 m in July 1913. It consists of a variable ballast dive using a skandalopetra tied to a rope. A companion on a boat recovers the diver by pulling the rope up after the descent, and keeps a watch on the diver from the surface.
Diving equipment is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable. This may be equipment primarily intended for this purpose, or equipment intended for other purposes which is found to be suitable for diving use.
In underwater diving, ascending and descending is done using strict protocols to avoid problems caused by the changes in ambient pressure and the hazards of obstacles near the surface such as collision with vessels. Diver certification and accreditation organisations place importance on these protocols early in their diver training programmes. Ascent and descent are historically the times when divers are injured most often when failing to follow appropriate procedure.
There are several categories of decompression equipment used to help divers decompress, which is the process required to allow divers to return to the surface safely after spending time underwater at higher ambient pressures.
The history of underwater diving starts with freediving as a widespread means of hunting and gathering, both for food and other valuable resources such as pearls and coral, By classical Greek and Roman times commercial applications such as sponge diving and marine salvage were established, Military diving also has a long history, going back at least as far as the Peloponnesian War, with recreational and sporting applications being a recent development. Technological development in ambient pressure diving started with stone weights (skandalopetra) for fast descent. In the 16th and 17th centuries diving bells became functionally useful when a renewable supply of air could be provided to the diver at depth, and progressed to surface supplied diving helmets—in effect miniature diving bells covering the diver's head and supplied with compressed air by manually operated pumps—which were improved by attaching a waterproof suit to the helmet and in the early 19th century became the standard diving dress.
The following outline is provided as an overview of and topical guide to underwater diving:
Investigation of diving accidents includes investigations into the causes of reportable incidents in professional diving and recreational diving accidents, usually when there is a fatality or litigation for gross negligence.
The following index is provided as an overview of and topical guide to underwater diving:
Diving support equipment is the equipment used to facilitate a diving operation. It is either not taken into the water during the dive, such as the gas panel and compressor, or is not integral to the actual diving, being there to make the dive easier or safer, such as a surface decompression chamber. Some equipment, like a diving stage, is not easily categorised as diving or support equipment, and may be considered as either.
In underwater diving, a downline is a piece of substantial cordage running from a point at the surface to the underwater workplace, and kept under some tension. It can be used as a guideline for divers descending or ascending, for depth control in blue-water diving, and as a guide for transfer of tools and equipment between surface and diver by sliding them along the downline at the end of a messenger line. A shotline is a special case of downline which uses a heavy weight at the bottom and a float at the top. A jackstay is a more lateral equivalent, that commonly follows a surface, and will not usually allow materials transfer without a messenger line from the destination end.
