Dive Lights for SCUBA Diving
A Scuba diver usually carries 3 dive lights. There is a saying, "Two is one and one is none" definitely applies!
The diver's primary dive light is usually the larger of the dive lights and that one that is turned on at the beginning of the dive. The backup light is usually a smaller light carried on a clip or in a BCD pocket, or some other easily accessible location. Backup lights are turned on and checked before the diver enters the water and then turned off and stowed. The backup light is there in case a problem develops with the primary light.
Canister lights are very popular among technical divers because of the extended burn time. A canister light has a light head connected to a battery canister that is usually worn on a hip belt. The light heads are often interchangeable and the battery canister provides more space for batteries than a typical dive light. Canister lights can often operate at full power for hours.
There are many different ways to mount and carry dive lights. The most common are handheld and wrist mount. A handheld dive light has either a pistol grip, a lantern grip, or no grip in the case of smaller lights. A diver will either use a wrist lanyard, retractor, or clip to carry the light. Smaller lights like backup lights are sometimes carried in a BCD pocket.