Diving equipment

• Scuba equipment: Primary cylinder(s), carried back-mounted or side mounted and open circuit regulator(s), or rebreather sets. Alternative air source such as bailout bottle or pony bottle, and decompression cylinders and their associated regulators. Secondary demand valve (Octopus).
• Surface supplied equipment: Helmet or full face mask, diver's umbilical, airline, bailout block, bailout cylinder and regulator.

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  Early twin cylinder set with twin hose regulator
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  Twin scuba cylinders with isolation manifold
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  Charging a small bailout cylinder from a larger aluminium scuba cylinder
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  Scuba regulator: First stage with primary and secondary demand valves, submersible pressure gauge and low pressure hose for BC inflation.
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  Technical diver with back mounted open circuit scuba and sling mounted decompression cylinders
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  Diving with a closed circuit rebreather
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  Russian made IDA-71 rebreather set
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  Heavy standard diving helmet, lightweight demand helmet and band mask
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  Diver wearing lightweight demand helmet

The underwater environment usually requires a diver to wear thermal, sting and abrasion protection.

• In cold water, a diving suit such as a dry suit (at temperatures of 0-10 °C), a wet suit (at temperatures of 21-25 °C), or a Hot water suit (surface supplied diving only) is necessary.
• Boiler suit overalls are often worn over the thermal protection suit by commercial divers as abrasion protection for the more easily damaged and expensive diving suit.
• In very warm water (temperatures of 26-30 °C), many types of tough, long, everyday clothing provide protection, as well as purpose made garments such as dive skins (made of lycra) and shorty wetsuits. In some cases, simple regular swimsuits are also used.[2]
• Diving gloves, including wetsuit gloves and dry gloves, mitts, and three-finger mitts
• Diving hoods
• Diving boots - With dry suits, the boots are usually integrated.
• Safety helmet for scuba diving. (Not part of the breathing apparatus.)
• Diving chain mail may be used as protection against bites by large marine animals
• Diver's cages may be used as protection against large predators
• Atmospheric diving suit provides complete isolation from the environment

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  Full wet suit
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  Dry suits
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  Short and full length wet suits
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  Wet suit boots
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  Neoprene diving gloves
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  Chain mail shark suit
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  Shark proof cage
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  Atmospheric diving suit

This equipment includes buoyancy control equipment and mobility equipment: Buoyancy control is achieved by ballasting with diving weights and compensating for buoyancy changes during the dive using a buoyancy compensator:

• Buoyancy compensator, also known as Buoyancy Control Device, BCD or BC - is usually a back mounted or sleeveless jacket style device which includes an inflatable bladder used to adjust the buoyancy of the diver under water, and provide positive buoyancy at the surface. The buoyancy compensator is usually an integral part of the harness system used to secure the scuba set to the diver. The earlier collar style buoyancy compensator is seldom used any more.
• Diving weighting system - to counteract the buoyancy of the diving suit and diver to allow descent. Professional divers may use additional weighting to ensure stability when working on the bottom

Mobility equipment allows the diver to move through the water and maneuver on the spot:

• Diver Propulsion Vehicle - to increase the range of the diver underwater
• Fins for efficient propulsion

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  Jacket buoyancy compensator
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  Diver propulsion vehicle (scooter)
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  Weight belt
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  Swim fins

These are the equipment used for monitoring the course of the dive and following the dive plan when undesirable events are avoided. They include planning and monitoring the dive profile, gas usage and decompression, navigation, and modifying the plan to suit actual circumstances.

• Depth gauge lets the diver monitor depth, particularly maximum depth and, when used with a watch and Decompression tables, also allows the diver to monitor decompression requirements. Some digital depth gauges also indicate ascent rate which is an important factor in avoiding decompression sickness
• Pneumofathometer is the surface supplied diving depth gauge which displays the depth of the diver at the surface control panel. It uses hydrostatic back-pressure on a low flow rate open ended air hose to the diver to indicate depth.
• Diving watch is used with depth gauge for decompression monitoring when using decompression tables. Largely superseded by dive computers, where elapsed time is one of the standard displays, and time of day may also be available.
• Dive timer is an instrument that displays and records depth and elapsed time during the dive. It is usually possible to extract the information after the dive. This function is often available as "Gauge setting" on dive computers.
• Diving compass for underwater navigation. This may be a regular magnetic compass, but is often a selectable function of a dive computer, where a miniature magnetometer is used.
• Submersible pressure gauge, also known as a "contents gauge" is used to monitor the remaining breathing gas supply in scuba cylinders.
• Dive computer helps the diver to avoid decompression sickness by indicating the decompression stops needed for the dive profile. Most dive computers also indicate depth, time and ascent rate. Some also indicate oxygen toxicity exposure and water temperature, and may provide other functions. A display of cylinder pressure is available on air-integrated computers, either via a direct high pressure hose, or remotely via a pressure transducer and through-water transmission.
• Distance line, guide line, or "come-home-line" can be used to guide the diver back to the start point and safety in poor visibility.
  • A cave line is a line laid by a diver while penetrating a cave to ensure that the way out is known. Permanent cave lines are marked with line markers at all junctions, indicating the direction along the line toward the nearest exit.

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  A depth gauge and submersible pressure gauge
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  Submersible pressure gauge
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  A surface supply panel for four divers showing four pneumofathometer gauges
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  A watch sized dive computer incorporating an electronic compass and the ability to display cylinder pressure when used with an optional transmitter
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  Dive computer showing the log of a previous dive
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  Nav finder and underwater compass - basic underwater navigation tools.
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  Diving compass in aftermarket wrist mount with bungee straps
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  Dive computers in compass mode
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  50 metres of line on a reel
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  Line arrow marker
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  A miniature submersible pressure gauge (mini SPG) used on pony cylinders

Underwater vision is significantly affected by several factors. Objects are less visible because of lower levels of natural illumination and are blurred by scattering of light between the object and the viewer, also resulting in lower contrast. These effects vary with wavelength of the light, and color and turbidity of the water. The human eye is unable to focus when in direct contact with water, and an air space must be provided. Voice communication requires special equipment, and much recreational diver communication is visual and based on hand signals.

• Masks allow the diver to see clearly underwater and protect the eyes.
  • Full face masks protect the face from dirty or cold water and increases safety by securing the gas supply to the diver's face. If it contains no mouthpiece, the diver can talk, allowing the use of communications equipment.
  • Half masks cover only the eyes and nose. The diver breathes from a separate mouthpiece on the regulator or rebreather.
• Diving helmets are often used with surface supplied diving. They provide the same benefits as the full face mask but provide a very secure connection of the gas supply to the diver and additionally protect the head.
• Underwater writing slates and pencils are used to transport pre-dive plans underwater, to record facts whilst underwater and to aid communication with other divers.
• Dive lights, which are usually waterproof and pressure rated torches or flashlights, are essential for safety in low visibility or dark environments such as night diving and wreck and cave penetration. They are useful for communication and signalling both underwater and on the surface at night. Divers need artificial light even in shallow and clear water to reveal the red end of the spectrum of light which is absorbed as it travels through water. Underwater video lights can serve the same purpose.
• Hand-held sonar for a diver can provide a synthetic view using ultrasonic signals emitted and processed by an electronic device and displayed on a screen.
• Ultrasonic signalling devices which attract the buddies attention by vibration have been marketed and may have some limited utility.[3]

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  A diving half mask provides clear sight and protection for the eyes.
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  A full face mask covers the eyes, nose and mouth.
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  One piece LED dive light with soft Goodman type handle
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  A "canister" style dive light

• Diver's safety harness, to which a lifeline may be attached, including Bell harness, AR vest, Jump jacket.
• Lifeline (or tether): A line from the diver to a tender at the surface control point, which may be used for:[4]
  • communications, by diving line signals,
  • to allow the diver to be found by the stand-by diver following the line,
  • to provide a guideline to the surface control point to guide the diver on return,
  • to assist the diver to maintain position in a current,
  • in an emergency, to recover the diver to the surface, and
  • in some cases lift the diver out of the water.
• Shotline: A line connecting a shot weight to a marker buoy, used to mark a dive site and provide a vertical reference for descent and ascent.
• Buddy line: A short line or strap connecting two divers in the water, used to prevent them from being separated in poor visibility and for communication by line signals.
• Jonline: A short line or webbing strap to tether the diver to the shotline in a current.
• Surface marker buoy, which indicates the position of the divers to people at the surface.
• DSMB - (Delayed, or deployable surface marker buoy), or decompression buoy which is inflated at the start of, or during the ascent, to indicate the position of the divers to the surface team, and as a signal that the divers are ascending.
• Cutting tool
  • Knife to cut lines, nets or to pry or dig. Not intended for personal protection against underwater predators as it is generally ineffective for this purpose.
  • Diver's net or line cutter. This is a small handheld tool carried by scuba divers to extricate themselves if trapped in fishing net or fishing line. It has a small sharp blade such as a replaceable scalpel blade inside the small notch. There is a small hole at the other end for a lanyard to tether the cutter to the diver.
  • Trauma shears. Very effective as a line cutter, with low risk of inadvertent injury or damage. Usually carried in a pocket or special purpose sheath.
• Automatic diver recovery devices which inflate the BCD if the diver stops breathing have been marketed. They are not generally used and the risks may outweigh possible benefits.

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  Front view of jacket style diver harness with removable weight pockets
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  scuba diver's net cutter. 7 inches long
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  Underwater Kinetics general purpose dive knife
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  Trilobite line cutter with sheath on diving harness
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  Trauma shears
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  DiverGuard automatically inflates the buoyancy compensator if the diver stops breathing.
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  Spool with line and double-ender clip
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  Dive reel with stored DSMB
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  A stainless steel line holder with a 20-metre line

Personal locator beacon for divers - sealed for immersion

Personal locator beacon for divers - open showing coiled antenna

The purposes of this class of personal equipment are to:[5]

• allow the support boat to monitor and find divers on the surface during or after a dive
• prevent the diver being struck by boat traffic
• mark the diver's position when drift diving or while at the decompression stop
• help rescue services in lifeboats and helicopters to locate the diver

Surface detection aids include:[5]

• Surface marker buoy, decompression buoy, delayed SMB, safety sausage or blob
• Red or yellow collapsible flag - high visibility, robust, usually stored bungeed to cylinder
• Whistle - cheap, will only be heard by people far from engine noise
• Torch or flashlight - if at sea after nightfall
• Strobe light - needs long-lasting batteries
• High pressure whistle - expensive but effective
• Orange dye marker - increases diver's visibility from search helicopters
• Mirror such as a used compact disc - to reflect sunlight or searchlights
• Red pyrotechnic flares - for helicopters and lifeboats
• ENOS Rescue-System
• Emergency position-indicating rescue beacon (EPIRB)
• Emergency locator beacon - A transmitter carried by the diver that can send a GPS position by VHF radio and/or Automatic identification system (AIS)
• Glow stick - for night diving

Vinyl toolbag with bolt snaps for securing to harness

Norwegian diving pioneer Odd Henrik Johnsen with underwater camera (1960's)

• Camera, strobe (flash), video lights and housing - for underwater photography or underwater videography
• Diving reel, spool or line holder to store and transport a distance line or line for a surface marker buoy. A spool is a small flanged cylinder with an axial hole, around which a length of line can be wound, and a line holder is a flat H-shaped piece of rigid sheet material on which a length of line can be wound, as an alternative to a reel or spool. The line may be used with a surface marker buoy or a delayed surface marker buoy, where negative buoyancy of the spool or line holder will help with unwinding the line underwater.
• Dry box to hold objects the diver needs to keep dry at depth (wallet, cell phone)
• Dry bag to carry items that must stay dry on the boat.
• Dive bag to hold equipment for travel.
• Tool bag to carry tools that may be required for the job. Various types and sizes are available.
• A rescue tether, or rescue rope, is a short lanyard or strap carried by a surface supplied stand-by diver to be used to tether an unresponsive diver to the standby diver during a rescue. It is attached at one end to a D-ring on the stand-by diver's harness, and has a clip at the other end which may be secured to a D-ring on the casualty's harness to allow the rescuer the use of both hands during the return to the bell or surface.

Surface supplied diver rescue tether with soft eye and bolt snap

Diving equipment may be exposed to contamination in use and when this happens it must be decontaminated This is a particular issue for hazmat diving, but incidental contamination can occur in other environments. Personal diving equipment shared by more than one user requires disinfection before use. Shared use is common for expensive commercial diving equipment, and for rental recreational equipment, and some items such as demand valves, masks, helmets and snorkels which are worn over the face or held in the mouth are possible vectors for infection by a variety of pathogens. Diving suits are also likely to be contaminated, but less likely to transmit infection directly.

When disinfecting diving equipment it is necessary to consider the effectiveness of the disinfectant on the expected pathogens, and the possible adverse effects on the equipment. Some highly effective methods for disinfection can damage the equipment, or cause accelerated degradation of components due to incompatibility with materials.

With the partial exception of breath-hold diving, the development of underwater diving capacity, scope, and popularity, has been closely linked to available technology, and the physiological constraints of the underwater environment which the technology allows divers to partially overcome. The timeline of underwater diving technology is a chronological list of notable events in the history of the development of underwater diving equipment.