Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team. In professional diving, diver communication is usually between a single working diver and the diving supervisor at the surface control point. This is considered important both for managing the diving work, and as a safety measure for monitoring the condition of the diver. The traditional method of communication was by line signals, but this has been superseded by voice communication, and line signals are now used in emergencies when voice communications have failed. Surface supplied divers often carry a closed circuit video camera on the helmet which allows the surface team to see what the diver is doing and to be involved in inspection tasks. This can also be used to transmit hand signals to the surface if voice communications fails. Underwater slates may be used to write text messages which can be shown to other divers, and there are some dive computers which allow a limited number of pre-programmed text messages to be sent through-water to other divers or surface personnel with compatible equipment.
The hand signal "OK"
Diver telephone c.1911
A hard-wired diver communications unit mounted in a waterproof box for convenience of transport and protection. The loose speaker has been added to increase output volume. There is a built in speaker behind the perforations on the panel.
Inside a Kirby Morgan 37 helmet showing the microphone in the oro-nasal mask, and one of the speakers at the top of the photo.
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.
Surface-supplied divers riding a stage to the underwater workplace
Mild barotrauma to a diver caused by mask squeeze
Views through a flat mask, above and below water
Recreational breath-hold divers in basic equipment with floats and catch bags suitable for collecting lobster or shellfish