موضوع تعبير عن cave diving

موضوع تعبير عن  cave diving

موضوع تعبير عن  cave diving

 Underwater diving

Underwater diving is an extreme sport in which a diver visits networks of cavities and caves filled with water. The equipment used varies with the circumstances, and varies depending on the range required for the return to the surface, but almost all the underwater dives are carried out using diving equipment, with specific configurations. Underwater diving is generally considered a type of technical dive because it takes place under the ceiling in non-free water, during most of the dive, and often involves decompression.

In France we have a lot of dive site, in the Lot for example, this is also called diving caving. England is also well known for this type of activity, like the United States and Mexico with their huge networks in Florida. Compared to dry caving and scuba diving, there are relatively few underwater diving practitioners. This is due in part to specialized equipment (such as rebreathers, scuba diving scooters and dry suits) and skill sets needed, and partly because of high potential risks, including decompression and drowning.

Despite these risks, water-filled caves attract divers, cave enthusiasts and cavers because of their often unexplored nature, and present divers with technical diving challenges. Underwater caves have a wide range of physical features, and may contain wildlife not found elsewhere.

The dangers of cave diving

Kilometers long and ramifications for underground networks

Kilometers long and ramifications for underground networks

Underwater diving is one of the most difficult and potentially dangerous types of diving or caving and presents many dangers. Underwater diving is a form of penetration diving, which means that in case of emergency a diver can not swim vertically to the surface due to the ceilings of the cave, and therefore must swim all the way back. Underwater navigation through the cave system can be difficult and exit routes can be at a considerable distance, forcing the diver to have enough breathing gas to make the return trip. The dive can also be deep, which leads to potential risks of deep diving.

Visibility can vary from almost unlimited to low or nonexistent, and can go from one extreme to the other in a single dive. Even though a less intensive type of diving called cave diving does not lead divers out of the reach of natural light (and usually no deeper than 40 meters, and for a maximum penetration of 60 meters), true cave diving may involve penetrations of several kilometers, far beyond the reach of daylight. The level of darkness created creates an environment impossible to see without multiple sources of lighting. Caves often contain sand, mud, clay, silt or other sediments that can further reduce underwater visibility in a few seconds when shaken.

Underground rivers can be crossed by very strong currents of water. Most caves emerge on the surface as springs or siphons. The springs have flowing currents, where the water comes out of the Earth and flows through the surface of the earth to throw itself into the rivers. Siphons have incoming currents where, for example, a surface river passes underground. Some caves are complex and have tunnels with outgoing currents, and other tunnels with incoming currents. If the currents are not properly managed, they can cause serious problems for the diver.

Underwater diving has been perceived as one of the deadliest sports in the world. This perception is questionable because the vast majority of divers who lost their lives in the caves did not receive specialized training or had inadequate equipment for the environment. Underground divers have suggested that cave diving is in fact statistically much safer than recreational diving because of the much greater barriers imposed by experience, training and cost of equipment.

There is no reliable global database that lists all cave diving deaths. However, such fractional statistics suggest that very few divers died using accepted protocols and using equipment configurations that are acceptable to the underground divers community.