Scuba

Kids as young as 10 years old can enroll in Junior Open Water courses and those 15 years and older can enroll in an Open Water course. When offered, Junior Open Water (diving with adult supervision only) certified divers are automatically upgraded to Open Water divers on their 15th birthday with no need for re certification. This can vary depending on the certification agency involved.

You'll also need to be in good health with no major health problems.

Because it can seriously injure or even kill you.

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Because a rapid ascent from the pressure of the deep can cause nitrogen bubbles to form inside your body. It is like taking the pressure off of a can of soda and watching the gas fizz all over. Now imagine a similar even taking place in your blood and the fluid in your tissues! This causes pain in the joints, and can even block the flow of blood in your body. Chaz

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To become a saturation diver you must first qualify and work as an air diver. Once you have a set amount of logged dive hours, working in surface supplied equipment in open water, you can complete a training course to gain your saturation (also known as mixed gas or closed bell) diving certification. The Underwater Centre in Tasmania provides ADAS diving certifications in both air and saturation diving, and The Underwater Centre in Fort William provides HSE diving certifications in both air and saturation diving. Both ADAS and HSE certificatoins are internationally recognised, allowing you to work anywhere in the world.

It is a device that looks like a bell and helps you dive into very deep places. the bell hosts the people in it sheilding them from the pressure.

I personally like the wetsuits form Patagonia. I also like the way their products are made and the way Patagonia thinks. Google them and you will be able to view their selection of apparel, and sports wear and gear.

WARNING: A BIT OF MATH FOLLOWS

A diver's buoyancy is determined by the mass of the water they (and their attached equipment) displace. Water density varies with temperature and salinity, but a good rule of thumb is that 1 cubic meter of water "weighs" about 1029 kilograms. That pencils out to about 64 pounds per cubic foot.

A typical diver displaces about 2.5 to 3 cubic feet of water. That's equivalent to about 160 to 192 pounds of sea water. Let's assume the diver displaces 2.5 cuft of water. That means that the water they displace will "support" 160 pounds. If the diver weights less than 160 pounds, she'll be positively buoyant and will float. If she weights more, she'll be negatively buoyant ad will sink. The ideal circumstance that a diver strives for is to be neutrally buoyant, so no energy is expended to keep from sinking or floating.

If our diver and her gear weigh 160 pounds, she'll be neutrally buoyant. In practice, our diver will carry enough weight to make her approximately neutrally buoyant. If she inhales air from her scuba cylinder, her chest cavity will expand, displacing a higher equivalent weight of water, and she'll ascend. If she exhales, she'll displace less water, and will descend.

This ideal neutrally buoyant state allows a diver to ascend and descend with minimal effort. In practice, however, things are constantly changing during a dive. Wetsuits compress with depth, meaning the deeper our diver goes, the less water she'll displace. So as she descends, she'll have a tendency to descend more quickly.

Her scuba cylinder displaces a constant amount of water, but the more air is used, the less it will weigh. This means that our diver will have a tendency to become more positively buoyant... she'll "float" more... as the dive progresses.

In order to adjust for all of these variables, divers wear a "Buoyancy Compensation Device" (BCD). This is generally a vest shaped bladder that can be inflated using air from the scuba cylinder. It is fitted with a dump valve that allows fine tuning of the amount of inflation, and thus the amount of water it displaces.

During a dive, our diver will adjust the amount of air in her BCD to maintain neutral buoyancy. Then she'll use her breathing to make fine adjustments in her vertical position.

Divers diving in colder environments will often use a dry suit in place of the wet suit worn by most recreational divers. This dry suit is filled with variable amounts of air from the scuba cylinder, much the same way a BCD is. A dry suit can be used alone, or together with a BCD, to control buoyancy.

In all cases, a diver will use a depth gauge, or a dive computer which measures depth, to monitor their depth throughout a dive.

The History of Scuba diving goes back through the centuries

People have been diving underwater throughout the ages, probably for as long as people have been swimming….. It may not have been Scuba but it is the beginnings of the quest throughout the history of scuba diving to be able to dive underwater and be able to breath underwater.

There are records, in some cases little more than myth, of the methods used and what was done while diving.

Read more at this site:

At depth you end up with compressed air in your lungs. If you hold your breath as you surface the gas expands and can tear the delicate structure of the lung. This can happen at much less depth than 30M. 100ft, which is a similar depth, is the depth used by the Royal Navy at HMS Dolphin in Portsmouth, England, to train submariners to escape from submarines. They are taught to exhale in a constant stream from the bottom of a tall tank to the surface. This is because it is quite unnatural when you are underwater to breathe all your air out and you want to hold your breath.

If you use scuba equipment and surface slowly breathing normally, you should not have any ill effects and it would only be under some kind of extreme emergency such as escaping from a submarine or losing all you air whilst solo diving that you would ever surface in that way. Naturally you should not dive on your own for that reason.

1839 Canadian inventors James Eliot and Alexander McAvity of Saint John, New Brunswick patent an "oxygen reservoir for divers", a device carried on the diver's back containing "a quantity of condensed oxygen gas or common atmospheric air proportionate to the depth of water and adequate to the time he is intended to remain below".[4] But was that SCUBA (Self Contained Underwater Breathing Apparatus) or ORFD? sounds like SCUBA, but... there is another entry:
1876: An English merchant seaman, Henry Fleuss, develops the first workable self-contained diving rig that uses compressed oxygen. This prototype of closed-circuit scuba uses rope soaked in caustic potash to absorb carbon dioxide so the exhaled gas can be re-breathed. but most people generally agree that MODERN SCUBA was invented by a couple of guys in France: 1943: Jacques Cousteau and Emile Gagnan invent and make an open-circuit diving breathing set, using a demand regulator which Gagnan modified from a demand regulator used to let a petrol-driven car run on a big bag of coal-gas carried on its roof during wartime shortages of petrol. Cousteau had his first dives with it. He made two more aqualungs: there were now 3, one each for Cousteau and his first two diving companions Frédéric Dumas and Taillez. His aqualung remained a secret until the south of France was liberated. This type of breathing set was later named the "Aqua-Lung". This word is correctly a tradename that goes with the Cousteau-Gagnan patent, but in Britain it has been commonly used as a generic and spelt "aqualung" since at least the 1950s, including in the BSAC's publications and training manuals, and describing scuba diving as "aqualunging".

SCUBA divers control their buoyancy to keep off the sea floor or from floating up to the surface, to avoid obstacles both above and below them, and to have a more relaxing dive with minimal physical effort. As a diver changes depth, they need to either add or release air from their buoyancy compensator (BC or BCD) to maintain neutral buoyancy. A diver in control of their buoyancy can move through the water with minimal fin input and breath control making the dive a lot more enjoyable (not to mention longer due to not using a lot of air inefficiently to maintain buoyancy control).

Buoyancy is not really used by scuba divers, but it does act against them. Since the human body and the gear during scuba diving is held up by the water, especially at farther down depths of the ocean, where the water is more dense because of the weight of the water and the air holding it down. Because of the buoyancy, the divers have to wear weights to offset this buoyancy. Since in scuba diving you use wetsuits, and since these suits have nitrogen bubbles to assist insulation, this makes you float even more. And since your cells contain lipids and other materiels that are lighter than the water, this makes you float even more. This means that scuba divers must use weights to offset the buoyancy.

Its called'The bends'

Both liquid and gas

Virtually zero. The reason I say virtually is that: * The actual number of divers being attacked by shark much less getting killed is so low as to be statistically insignificant and... * Of the few that do, some don't practive even the most basic safety (consider Valerie Taylor, who made a chain-mail suit, created a feeding frenzy, and jumped into the middle to see if the suit prevented shark attack (and it did -- she wasn't killed -- only a slight nick). Basic rules of safety are: * Don't look like a fish in trouble. That's what shark eat. Don't look like food. Don't flop around -- swim purposefully and smoothly. * Don't smell like a fish in trouble. While shark probably don't react much at all to the scent of human blood, they do detect fish blood very well -- that's their prey. Clean off fish blood and don't tow bleeding strings of fish in dangerous waters. * If you are approached aggressively by a shark, back away smoothly. Shark are territorial in some cases. Get out of range. How will you know if the shark is being aggressive? You'll KNOW. If you aren't sure, act respectfully, keep a distance, and don't act like sharkbait. [[User:Cjonb|Cjonb]] 23:49, 2 Jun 2008 (UTC)

a divice that supplies air to underwater swimmers

40 feet (12 meters) to 100 feet (30 meters).

probably, actually I'm almost positive there are.

I guess if you do not know how to swim yet, so yes You Have to Learn to Swim beforehand, but if you know how to swim then the answer is You Don't Need to Know How to Swim again unless you forget, aka You Have to Know How to Swim.

It depends on the size of the tank. The standard tank used at most scuba diving training facilities use an aluminum 80. The tank weighs around 21 lbs. full. As the tank is used during diving it becomes more boyant, meaning that you need to use more weight at the end of the dive then you need at the beginning.