Scuba

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.

Perhaps the greatest risk is panic. When people panic, they tend to hold their breath and, when they ascend, the air in their lungs expands and can rupture a lung (or other similar medical conditions). It's easy to avoid though -- just breath normally. Staying down too long is also a problem. When you certify as a SCUBA diver, you'll be taught all about that. Another problem are big waves. The solution? Dont Dive When The Waves Are Big (like I had to say that! LOL ). Other dangers include hypothermia -- getting too cold, and exhaustion. The remedy for those is to get back on the beach or boat before they happen. I wouldn't worry about creatures eating me. You're more likely to get hit by lightning. If you NEED to worry about creatures, in California, far more people step on Sea Urchins than get attacked -- so watch where you step.

Diving is based on being calm and relaxed. If you can do that, the risks are very few.

but, the TRUE risk of SCUBA diving is that you will fall so in love with it that you will think of nothing else and feel empty inside until the next time you DO get to go SCUBA diving again

Let's take a moment to define some terms. The typical value used to represent air pressure at sea level is 14.7 pounds per square inch or 14.7 PSIg. You can think of 14.7 pounds as the "weight" of the entire column above a one square inch surface. For convenience, this pressure is also termed one "Atmosphere" or atm. The formal definition of one atm is 1.01325 x 105 pascals. Think of one atm as "about 15 PSIg".

Unlike air, water has the property of not being compressible. The means a given volume of water "weighs" the same, regardless of depth. Accordingly, water pressure increases linearly with depth. It increases about 1/10 atm for each foot of sea water, or 1 atm every 33 feet.

A diver at 33 feet of sea water is under a total pressure of 2 atm - one atm of air and one atm of water. At 66 feet, the total pressure is 3 atm, and so on. At 660 feet, the total pressure is 21 atm (660/33) of water plus one of air).

No you cannot in any of the 50 states the laws may say that they may be legal at 16 but that is a lie if you call tattoo parlors in any area of that state they do not take the risk.

I disagree. As far as South Carolina goes specifically, I can't say for certain. As for the above answer that says you can't get tattooed in any of the 50 states at age 17, that is completely WRONG. I have been a professional tattoo artist for over 10 years, and can tell you with certainty that it depends on the state laws. I tattooed in North Carolina and it was illegal for anyone to get tattooed under the age of 18. I also tattooed in Alabama where there is no regulated age with parental consent. I personally do not tattoo minors, however it is not illegal in some states and you can find plenty of artists that will happily tattoo you with your parents' consent.

Scuba diving is very money-intensive. If you rent basic equipment, figure on spending $100 per day, depending on how heavy your exposure protection (wetsuit) is. Buying basic equipment can easily run $500 or more, plus maintenance and repairs. A dive computer ranges from under $100 for a simple electronic gauge to several hundred dollars for a computer designed for multiple gas mixtures and high-end features.

Add in the fees for training courses and ticket prices to travel to warm-water dive sites, and it all adds up fast.

It's all worth it.

It sounds like you already know the answer you want, but the answer depends upon which certification agency you want the answer for. For most "sport" agencies, the maximum operating partial pressure is 1.40 with an emergency contingency pressure of 1.60. However ANDI, sets the maximum operation pressure at 1.45 and some technical agencies set it at 1.3 once you go deeper than 100 feet or 30 meters.

Self Containing Underwater Breathing Apparatus

1823 Charles Anthony Deane, an English inventor, patents a "smoke helmet" for fighting fires. At some point in the next few years it is used as a diving helmet as well. The helmet fits over a man's head and is held on with weights; air is supplied from the surface through a hose. In 1828 Charles and his brother John Deane market the helmet with a "diving suit." The suit is not attached to the diving helmet but only secured with straps; thus the diver cannot bend over without risking drowning. Even so, the apparatus is used successfully in salvage work, including the removal of some canon from the Royal George in 1834-35

Equipment changes depending on the location of the dive and purpose. Basic equipment include, wetsuit, fins, snorkel and mask, lead weight, scuba tank, BCD (Buoyancy Compensation Device), and Regulator.

You can't let it get in when you are breathing from it, but you can get it into your tank if you don't keep your cap on your tank. Another way is from pressing the button on your second stage, so it can get into your tank.

If the gas is normal air (~20-22% oxygen), the maximum recommended depth of most dive organisations is in the region of 50-60m. The reason for this is that the deeper you go, the higher the pressure of the water. For example, on the surface, the pressure is 1 bar, 10m is 2 bar, 20m is 3 bar 30m is 4 bar etc.

Oxygen becomes toxic to the human body at about 1.6 bar so if you are at 70m, with a mix of 20% oxygen, you are at 8 bar of pressure. At 8 bar, the parital pressure of oxygen is 1.6 bar, enough to become toxic. So compressed air becomes dangerous at 70m so most organisations advise to go no deeper than 50-60m.

If you use a different gas blend, such as Nitrox ar Trimix, the amount of oxygen is different so the depths are different too.

In summary, on compressed air, the maximum is about 70m, recommended 50-60m max.

There are two principal ways that gas solubility affects scuba divers:

Narcosis. The lipid solubility of gas determines the narcotic effect at depth. For most divers, this is not really noticeable until they reach about 100 feet in depth, when they start to suffer to a greater or lesser degree from narcosis (often misleadingly called "Nitrogen narcosis", or "rapture of the deep"). Technical divers who go to greater depths often use helium gas mixes - due to the very low lipid solubility of helium, it has very little narcotic affect, leaving the diver clear headed.

Decompression sickness. Breathing gases under pressure causes the body to also absorb those gases. If a diver stays at depth for a long time, her tissues can absorb a great deal of gas, and if she ascends too quickly, bubbles can form in her bloodstream, which leads to decompression sickness (also called "the bends" or "caisson's disease"). Divers can avoid DCS by either breathing oxygen rich mixtures like nitrox (the body metabolises oxygen, so it doesn't get absorbed) or limiting their depth or bottom teams to avoid excessive gas absorbtion. Divers who stay too deep or too long need to make decompression stops at shallow depths before surfacing, to allow the gas to diffuse out of their tissues safely.

To prevent decompression illness (usually shortened to dci, non divers commonly refer to it as the bends as ur limbs flex and bend, my biology teacher, also a diver, told me so a while ago). When u go deep, the air breathe is at a higher pressure, as the water pressure tries to squash ur lungs, u just take in more air-compressed. Because the air is compressed, u r actually breathing more of it, meaning ur also taking in more nitrogen. As it is inert, it just dissolves into ur blood, but as the pressure is released, the dissolved nitrogen rushes out in bubbles, like when u open a bottle of fizzy drink. The body can only cope with so much bubbles in the blood, so our ascent is always slow. Dives deeper than 40 metres, using air (i.e. not using a special blend of gas) usually require staged decompression - where u go to one depth, stop, go to a shallower one, and stop and so one, to let the bubbles slowly escape. It is common practice that we make a 'safety stop' no matter what depth we dive to just to be on the safe side. It is a stop at 5 metres, and if all has gone well, it is for 3 minutes. We also have time limits for depths, deeper u go, the shorter the limit, as the body cant cope with too much dissolved nitrogen, known as residual nitrogen. If u go over this time limit by no more than five minutes, the safety stop is made at 5m again but for 8 minutes. Ifu exceed a time limit by more than 5 minutes, the safety stop must be 15 minutes - air/breathing gas supply allowing. Obviously if you're running out of air, you surface and seek medical attention before its too late.