Weight Belts
Weight belts are made of synthetic fibers or rubber and are fastened by a buckle which can be easily unbuckled in case of emergency. One kilogram weights are strung up on to compensate the negative buoyancy. 

Did you know : Rubber weight belts are used in deep dives because the body is exposed to great water pressure and it shrinks. Rubber is elastic and it shrinks too. Thus, the belt cannot loosen from the waist.

Underwater knives
They are quite important and useful in case of emergency. It is recommended that every diver carries a knife. The underwater knives have different shapes but all have a comfortable rubber or plastic handle. They can be carried either on the leg near the ankle, the tight or on the waist. 
 

Underwater watches These are special watches with a high resistance to pressure and glowing ciphers.

Depth gauges
These are electronic devices that can give the exact depth at which the diver is. 

Underwater compasses
It is of significant help to underwater navigation especially when there is low visibility. The underwater compass is actually a magnetic compass put in a water- and pressure-proof case. It is worn on the wrist like a watch.

Underwater slate
It can be made of a sand-papered piece of acrylic plastic and used with a pencil. Semimatte plastic sheets can be bought and used in the same way for writing down information.

Underwater lights
These are different kinds of torches or lamps which are pressure- and water-proof. They usually have neutral or slightly positive buoyancy. 

Signal devices
Signal devices are used when a diver surfaces away from the ship. They emit light and release smoke. 

Safety lines
They are made of synthetic fibers and are used to assist the diver in a cave, under ice or into a strong current. They link the diver with the surface crew or with another diver.

Floats
They signal the location of the diver to the surface crew or the passing boats. They should carry the diver’s flag.

Flotation devices
These are employed in emergency rescues of divers. They are produced in different shapes and sizes but it is important that all of them keep the face of the unconscious diver out of the water when he surfaces. Every diver must be trained how to use the flotation device he is wearing in order to prevent himself from a quick ascent which may cause decompression sickness. The flotation devices are usually inflated by a cylinder full of carbon dioxide attached to them or with air from the scuba cylinder. 

Underwater communication devices
Underwater communication is achieved through different kinds of hardwire, acoustic or non-acoustic wireless systems. They allow the diver (if he is with a helmet) to talk to his team. They can’t be used with wet and dry suits.

Underwater means of fast movement
Underwater sleds 
These are devices which divers use to swim quickly and without any effort and waste of energy. They are produced with on or two engines and there are some models which can carry two or three divers. For covering greater distances, wet submarines are used. They are called “wet” because  the diver stays in water. They keep the diver from the current which the moving device creates. The can carry equipment and can have a stationary breathing system. 

Decompression chamber
Decompression chambers are used for decompression of divers who have just left the water after a deep dive or are about to enter straight into great depths. The decompression chamber can be a single-seated or many-seated and usually has an oval shape. Most of the chambers mounted on a ship or near the diving spot are charged with breathing gases from scuba cylinders. It can be also used for recompression o f divers.
Recompression chamber
This device is employed in laboratories and medical centers to treat divers suffering from decompression sickness. The diver is placed in the chamber where the pressure is increased to the depth at which the gas bubbles have started to form. Then, the pressure is slowly decreased so that complete desaturation takes place.

ATTENTION: (It concerns all of the above without the chambers)
1.  All equipment which has been in salt water must be washed with  fresh water!
2.  The rubber parts of the equipment must not be exposed to the sun.
3.  Rubber must be occasionally washed with soap!
4.  Equipment should be kept in a dry place. 
5.  Rubber parts should be covered with talcum if they are not going to be used for a long time
6.  Some metal pieces of equipment, like knives, regulators, valves, etc. should be oiled at regular intervals.