Scuba diving may be performed for a number of reasons, both personal and professional. Most people begin though recreational diving, which is performed purely for enjoyment and has a number of distinct technical disciplines to increase interest underwater, such as cave diving, wreck diving, ice diving and deep diving.

Divers may be employed professionally to perform tasks underwater. Most of these commercial divers are employed to perform tasks related to the running of a business involving deep water, including civil engineering tasks such as in oil exploration, underwater welding or offshore construction. Commercial divers may also be employed to perform tasks specifically related to marine activities, such as naval diving, including the repair and inspection of boats and ships, salvage of wrecks or underwater fishing, like spear fishing.

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, infiltration behind enemy lines, placing mines or using amanned torpedo, bomb disposal or engineering operations. In civilian operations, many police forces operate police diving teams to perform search and recovery or search and rescue operations and to assist with the detection of crime which may involve bodies of water. In some cases diver rescue teams may also be part of a fire department or lifeguard unit.

Lastly, there are professional divers involved with the water itself, such as underwater photography or underwater filming divers, who set out to document the underwater world, or scientific diving, including marine biology and underwater archaeology.

TYPE OF DIVING	CLASSIFICATION
Aquarium maintenance in large public aquariums	Commercial, scientific
Boat and ship inspection, cleaning and maintenance	Commercial, naval
Cave diving	Technical, recreational
Civil engineering in harbors, water supply, and drainage systems	Commercial
Crude oil industry and other offshore construction and maintenance	Commercial
Demolition and salvage of ship wrecks	Commercial, naval
Diver training for reward	Professional
Fish farm maintenance	Commercial
Fishing, e.g. for abalones, crabs, lobsters, pearls, scallops, sea crayfish, sponges	Commercial
Frogman, manned torpedo	Military
Harbor clearance and maintenance	Commercial, military
Media diving: making television programs, etc.	Professional
Mine clearance and bomb disposal, disposing of unexploded ordnance	Military, naval
Pleasure, leisure, sport	Recreational
Underwater photography	Professional, recreational
Policing: diving to investigate or arrest unauthorized divers	Police diving, military, naval
Search and recovery diving	Commercial
Search and rescue diving	Police
Spear fishing	Professional (occasionally), recreational
Stealthy infiltration	Military
Marine biology	Scientific, recreational
Underwater tourism	Recreational
Underwater archaeology (shipwrecks; harbors, and buildings)	Scientific, recreational
Underwater welding	Commercial