Open water diving is underwater diving in an open water environment, where the diver has unrestricted access by way of a direct vertical ascent to the breathable air of the atmosphere. Other environmental hazards may exist which do not affect the classification. Open water diving implies that if a problem arises, the diver can directly ascend vertically to the atmosphere to breathe air, so it is also understood that, with this restriction, a staged decompression obligation is incompatible with open water diving, though it does not affect classification of the environment. This meaning is implied in the certifications titled Open Water Diver and variations thereof.
Wreck diving is recreational diving where the wreckage of ships, aircraft and other artificial structures are explored. The term is used mainly by recreational and technical divers. Professional divers, when diving on a shipwreck, generally refer to the specific task, such as salvage work, accident investigation or archaeological survey. Although most wreck dive sites are at shipwrecks, there is an increasing trend to scuttle retired ships to create artificial reef sites. Diving to crashed aircraft can also be considered wreck diving. The recreation of wreck diving makes no distinction as to how the vessel ended up on the bottom.
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.
A diving weighting system is ballast weight added to a diver or diving equipment to counteract excess buoyancy. They may be used by divers or on equipment such as diving bells, submersibles or camera housings.
A diving shot line, shot line, or diving shot, a type of downline or descending line, is an item of diving equipment consisting of a ballast weight, a line and a buoy. The weight is dropped on the dive site. The line connects the weight and the buoy and is used by divers to as a visual and tactile reference to move between the surface and the dive site more safely and more easily, and as a controlled position for in-water staged decompression stops. It may also be used to physically control rate of descent and ascent, particularly by surface-supplied divers.
A dive boat is a boat that recreational divers or professional scuba divers use to reach a dive site which they could not conveniently reach by swimming from the shore. Dive boats may be propelled by wind or muscle power, but are usually powered by internal combustion engines. Some features, like convenient access from the water, are common to all dive boats, while others depend on the specific application or region where they are used. The vessel may be extensively modified to make it fit for purpose, or may be used without much adaptation if it is already usable.
Diver rescue, usually following an accident, is the process of avoiding or limiting further exposure to diving hazards and bringing a diver to a place of safety. A safe place generally means a place where the diver cannot drown, such as a boat or dry land, where first aid can be administered and from which professional medical treatment can be sought. In the context of surface supplied diving, the place of safety for a diver with a decompression obligation is often the diving bell.
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.
Canoe diving and Kayak diving are recreational diving where the divers paddle to a diving site in a canoe or kayak carrying all their gear in or on the boat to the place they want to dive. Canoe or kayak diving gives the diver independence from dive boat operators, while allowing dives at sites which are too far to comfortably swim, but are sufficiently sheltered.
Diving equipment, or underwater 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.
Dive planning is the process of planning an underwater diving operation. The purpose of dive planning is to increase the probability that a dive will be completed safely and the goals achieved. Some form of planning is done for most underwater dives, but the complexity and detail considered may vary enormously.
Scuba skills are skills required to dive safely using self-contained underwater breathing apparatus, known as a scuba set. Most of these skills are relevant to both open-circuit scuba and rebreather scuba, and many also apply to surface-supplied diving. Some scuba skills, which are critical to divers' safety, may require more practice than standard recreational training provides to achieve reliable competence.
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 following outline is provided as an overview of and topical guide to underwater diving:
The following index is provided as an overview of and topical guide to underwater diving: Links to articles and redirects to sections of articles which provide information on each topic are listed with a short description of the topic. When there is more than one article with information on a topic, the most relevant is usually listed, and it may be cross-linked to further information from the linked page or section.
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.
A jackstay is a cable or bar between two points to support and guide a load between those points, or as an anchor to attach something to be constrained along that line. The term is mostly used in a marine context and originated on sailing ships. Note the use of the term 'stay' implies load bearing working rigging. In diving it is also a line to guide the movements of a diver between the endpoints.
The following index is provided as an overview of and topical guide to underwater diving:
