Diving activities
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.
There are various aspects of professional diving that range from part-time work to lifelong careers. Professionals in the recreational diving industry include instructor trainers, diving instructors, assistant instructors, divemasters, dive guides, and scuba technicians. A scuba diving tourism industry has developed to service recreational diving in regions with popular dive sites. Commercial diving is industry related and includes civil engineering tasks such as in oil exploration, offshore construction, dam maintenance and harbour works. Commercial divers may also be employed to perform tasks related to marine activities, such as naval diving, ships husbandry, marine salvage or aquaculture. Other specialist areas of diving include military diving, with a long history of military frogmen in various roles. They can perform roles including direct combat, reconnaissance, infiltration behind enemy lines, placing mines, bomb disposal or engineering operations.
In civilian operations, police diving units perform search and rescue operations, and recover evidence. In some cases diver rescue teams may also be part of a fire department, paramedical service, sea rescue or lifeguard unit, and this may be classed as public safety diving. There are also professional media divers such as underwater photographers and videographers, who record the underwater world, and scientific divers in fields of study which involve the underwater environment, including marine biologists, geologists, hydrologists, oceanographers and underwater archaeologists.
The choice between scuba and surface-supplied diving equipment is based on both legal and logistical constraints. Where the diver requires mobility and a large range of movement, scuba is usually the choice if safety and legal constraints allow. Higher risk work, particularly commercial diving, may be restricted to surface-supplied equipment by legislation and codes of practice.
Diving procedures
The standard procedures and activities essential to safe diving in the chosen diving mode, using the chosen diving equipment, and in the chosen diving environment are inherently part of the activities of a dive. Monitoring the dive profile, gas supplies, decompression status, relative positions of the divers and communication associated with these are all standard operating procedures. Contingency procedures associated with the diving mode, equipment and foreseeable diversions from the dive plan may also be necessary. These activities may be considered as occurring in the background, as in most cases they are not the reason for the dive.Navigation
Navigation is a common activity during dives. Diver navigation, termed "underwater navigation" by scuba divers, is a set of techniques—including observing natural features, the use of a compass, and surface observations—that divers use to navigate underwater. Free-divers do not spend enough time underwater for navigation to be important, and surface supplied divers are limited in the distance they can travel by the length of their umbilicals and are usually directed from the surface control point. On those occasions when they need to navigate they can use the same methods used by scuba divers. When it is critical for safety to return to a specific place, a distance line is generally used. This may be laid and left in place for other divers, or recovered on the return leg. Use of distance lines is standard in penetration diving, where the divers cannot ascend directly to the surface at all times, and it is possible to lose track of the route out to.Searches
Searches are a fairly common diving activity, and may be the primary purpose of the dive, part of a more complex activity plan, or incidental. Underwater searches are procedures to find a known or suspected target object or objects in a specified search area under water. A search method attempts to provide full coverage of the search area, by using a search pattern, which should completely cover the search area without excessive redundancy or missed areas.Operation of special equipment
A diver propulsion vehicle is a type of diving equipment sometimes used by scuba divers to increase range underwater. Range is restricted by the amount of breathing gas that can be carried, the rate at which that breathing gas is consumed, and the battery power of the DPV. Time limits imposed on the diver by decompression requirements may also limit safe range in practice. DPVs have recreational, scientific and military applications.Exploration
There is often an element of exploration in diving activity, as it is common to dive in an unfamiliar place. This exploration may be casual or focused on gathering information which can be shared or recorded and published for use by others. A large part of the waters accessible to divers remains virtually unknown, and has not been surveyed or mapped in detail, and in many cases, has not yet been visited by divers. Exploration has been identified as one of the major motivations for recreational diving, but it is mostly casual and seldom results in recorded reports which can be of use to others.Underwater work
Underwater work is usually done by professional divers who are paid for their work. The procedures are often regulated by legislation and codes of practice as it is an inherently hazardous occupation and the diver works as a member of a team. Due to the dangerous nature of some professional diving operations, specialized equipment such as an on-site hyperbaric chamber and diver-to-surface communication system is often required by law, and the mode of diving for some applications may be regulated.There are several branches of professional diving, the best known of which is probably commercial diving and its specialised applications. There are also applications in scientific research, marine archaeology, fishing and aquaculture, public service, law enforcement, military service, media work and diver training. Specialist training may be required for some aspects of this work.
Commercial diving
Commercial diving may be considered an application of professional diving where the diver engages in underwater work for industrial, construction, engineering, maintenance or other commercial purposes which are similar to work done out of the water, and where the diving is usually secondary to the work.Offshore diving
Commercial offshore diving, sometimes shortened to just offshore diving, generally refers to the branch of commercial diving, with divers working in support of the exploration and production sector of the oil and gas industry. The work in this area of the industry includes maintenance of oil platforms and the building of underwater structures. In this context "" implies that the diving work is done outside of national boundaries. Technically it also refers to any diving done in the international offshore waters outside of the territorial waters of a state, where national legislation does not apply. Most commercial offshore diving is in the exclusive economic zone of a state, and much of it is outside the territorial waters. The type of work includes tasks such as wellhead completion, submarine pipeline monitoring and inspection, assembly of manifolds and work on moorings, including rigging, lifting, and assembly of components.Salvage diving
Salvage diving is the diving work associated with marine salvage, the recovery of all or part of ships, their cargoes, aircraft, and other vehicles and structures which have sunk or fallen into water. In the case of ships it may also refer to repair work done to make an abandoned or distressed but still floating vessel more suitable for towing or propulsion under its own power. The recreational/technical activity known as wreck diving is generally not considered salvage work, though some recovery of artifacts may be done by recreational divers.Most salvage diving is commercial or military work, depending on the diving contractor and the purpose for the salvage operation, Similar underwater work may be done by divers as part of forensic investigations into accidents, in which case the procedures may be more closely allied with underwater archaeology than the more basic procedures of advantageous cost/benefit expected in commercial and military operations.