SCUBA divers on land often seem loaded down with huge amounts of equipment, and their appearance certainly does not suggest that they are about to take it easy underwater. You may not believe that it all becomes weightless once submerged - but it does.
So whats it all about What do all those hoses and belts and buckles and cylinders do What equipment do you actually need in order to dive
First, you need a mask to let you see properly underwater. Then you need fins to let you make the most of your energy when propelling yourself along, and a snorkel - a simple tube - so you can swim at the surface without wasting energy bringing your head up to breathe.
To stay underwater you need SCUBA, a Self Contained Underwater Breathing Apparatus. Normally divers use open-circuit scuba, which means they breathe from a reservoir of air in a cylinder carried on the back, and exhale freely into the water. A regulator valve provides the mechanism to allow this.
Normally divers use a single-hose regulator. This name may seem a little odd given that it usually has a plethora of hoses sprouting from it.
This is because the air used by the diver for breathing is also used for other purposes. Air is used to feed a device for buoyancy control, called a BC (Buoyancy Compensator). This is a jacket that works as a swimbladder works for a fish, enabling the diver to maintain a constant depth without sinking or floating upwards.
The jacket is also used to attach the air cylinder to the divers back, and its harness is used to clip on smaller accessories.

The list of ancillary equipment that a diver might use is almost endless. It all depends on what he or she plans to do underwater.

The other hoses feed gauges or computers for air-supply management. There is usually a spare hose and mouthpiece for use by another diver in case of an emergency, known as an octopus, and there can be a further hose for feeding air to the inside of a drysuit.
Water conducts heat very efficiently, which means that divers get cold underwater, however warm it may be. Every diver needs a diving suit of some kind and these can vary from very lightweight dive skins or wetsuits to drysuits which, as the name implies, keep the diver dry and allow him to wear warm clothes underneath. The drysuit needs an air supply to prevent it getting squeezed at depth, and this uses another air-feed hose from the regulator.
The inherent buoyancy of a suit makes a diver float, so lead weights are normally worn on a weightbelt to compensate.
Wrist-mounted decompression computers look after a divers well-being by helping to avoid experiencing the bends, and a compass helps in navigation. Sometimes these instruments are mounted on a console at the end of a hose.
A submersible lamp is used to light the way at night, inside wrecks and caverns, and in other low-light conditions.
A knife is used to sort out any possible entanglement in old fishing line, and a surface buoy attached to a line and winder-reel allows people at the surface to track the divers position.
Modern-thinking divers do not kill the marine life or plunder dive sites - they leave only bubbles and take only photographs. Underwater photography is an increasingly popular hobby - but thats another story.