- A shorty is a wetsuit that has short legs and sleaves, it should only be worn in very warm water as it is still easy to get cold if in the water for a long time. In most cases a full wet suit is preferable.
- A full suit can be either wet or dry. The thickness of the suit needs needs to be matched to the water temperature a the depth you will be diving, this is often much colder than at the surface.
- A hood provides thermal protection for the head but at the cost of limiting movement.
- Gloves provide thermal protection for the hands thicker gloves are warmer but make it more difficult to operate equipment.
- A mask is essential as it provides an airspace which allows the eyes to focus. The nose must be enclosed withn this airspace to allow equalisation and water clearing
- A snorkel will allow divers to breathe at the surface with their faces in the water. Some training agencies suggest the snorkel should be permenantly attached to the mask ready for use
- Fins are an essential part of the diver or snorkeller's equipment as they allow the diver to swim without using their arms.
- All divers should carry some kind of cutting implement to free themselves should they become entangled, some divers carry line cutters or scissors. Placement of the tool varies but it should be possible to reach it easily with either hand
- A torch is essential equipment for night dives or in overhead environments (when at least one backup should also be carried.) Torches are also useful during the day to show the true colours of objects when diving at depth
- Every diver should carry instruments to record the depth and duration of their dive. Most divers chose to use a computer, which also calculates their remaining no stop time or decompression requirements. More complex computers can be used for staged decompression, mixed gas or rebreather dives
- A reel is essential when entering overhead environments such as wrecks, caves or under ice where it is used to prevent the diver from getting lost. Reels can be used in open water in a similar way or for searchess. They are also commonly used by divers in conjunction with SMBs.
- A SMB (Surface Marker Buoy) is used to mark the position of divers while they are under water. This is particularly important if the divers are carrying out a drift dive or are diving in an area frequented by boats.. A delayed SMB may be deployed from underwater by the diver when required.
- Divers should be weighted so the they are neutrally buoyant with all their equipment in place an their tanks empty. A weightbelt is required to compensate for the buoyancy provided by the wet or dry suit the diver is wearing. A weighbelt should have a quick release buckle so that the weight can be dumped in an emergency. Some divers use weights that are integrated into their BCD and so don't need a weightbelt
- Divers need to be able to adjust their buoyancy while diving to compensate for the compression of their suits due to changes in pressure. This is accomplished with a BCD (Buoyancy Control Device) which can be inflated, with air from the tank via the regulator, and deflated via a dump value. Most BCDs wrap around the diver like a waistcoat.
- A wing is just a different style of BCD, the difference being that all the buoyancy is at the back of the diver and so the chest area is clear for other equipment. For this reason wings are preferred by technical divers carrying multiple tanks.
- Every diver should carry an AAS (alternate air source.) The most simple AAS is an octopus, a secondary mouthpiece that can be used in an emergency. In the event of an air failure the diver uses his or her buddy's octopus to breath and the pair then exit the water. This method requires that the buddy is nearby and alert to potential problems.
- Twin tanks provide both a larger amount of air and additional safety, as in the event of the failure of one air supply the diver has another. Twin tanks are used when in overhead environments or when carrying out long dives. Twin tanks are also used when diving solo.
- A pony bottle is an AAS (alternate air source) it should only be used in an emergency. It has the anvantage over an octopus that a diver can use his or her own pony bottle without needing to rely on their buddy. The disadvantage is that the diver now has more equipment to carry and will create more drag in the water.
- A stage bottle is similar to a pony bottle but it is carried on the front. Although a stage bottle could be used as an AAS it is typically carried containing a rich nitrox mix for staged decompression. The diver switches to the stage bottle during their ascent and breathes an oxygen / nitrogen mix containing more than 21% oxygen (typically 50%) this either makes the dive safer for the diver or reduces the time required for their decompression.
