Scuba diving: Among those who do it, it's more than a sport, it's a way of life. For the uninitiated, it's fascinating, and more than a little scary. Which is as it should be -- scuba diving is considered an extreme sport, and it does cause about 13 deaths per 100,000 divers. And yet, this fatality rate is on par with jogging. So is scuba truly dangerous? Or just misunderstood?
A few facts about scuba: Technically, it should be written SCUBA, as it's an acronym for Self Contained Underwater Breathing Apparatus. However, few people actually use the capitals, just like few people remember that the word "SCUBA" doesn't refer primarily to a form of diving, but to the equipment itself. The gear that a diver takes down is called a "scuba set," and its primary components are the tank of compressed air, the hoses and the mouthpiece through which the diver breathes.
There's a good bit to learn about scuba, even for simple recreational divers. (Examples of non-recreational divers include military "frogmen," underwater photographers and salvage operators). That's why divers have to be certified ... which brings us to our quiz! Whether you've already been diving, or whether it remains a persistent daydream for you, we're here to test your knowledge on all things scuba. Think you're ready to take the plunge? Try our quiz now!
If you can't swim, there's not a lot a scuba instructor can do for you!
If you're being a perfectionist, the word SCUBA should be in all-caps. It stands for "Self Contained Underwater Breathing Apparatus." In this quiz, we'll be lowercasing the word, which is how most divers (and others) write it.
This is the minimum standard to be a diver. It's also referred to as "being able to dive unsupervised," which does NOT mean alone! It means without an instructor.
The joint pain caused by decompression sickness is termed "the bends." This happens when a diver comes up from depth too quickly, and can have worse effects.
This is one of the few things non-divers know about scuba: to prevent the "bends," make several stops on the ascent. And although people expect Vitamin D to help with *everything* nowadays, it's not a decompression-sickness preventive.
Buoyancy is an easy concept for non-divers to grasp. We see it in swimming pools and bathtubs and so on. However, in scuba diving, buoyancy and its management becomes a much more complicated subject.
Neutral buoyancy, as you'd imagine, means you're neither being pulled up nor down. This allows more energy to be devoted to locomotion and exploration.
A cylinder or tank carries a diver's supply of compressed air. The compression allows a diver to stay under longer -- a normal volume of air wouldn't last very long.
You'll start your training in a "confined water" situation. Learning the basics in a swimming pool obviously lessens the risks.
A sea is an example of open water. However, it's far from the only kind. Open water includes lakes, rivers, ponds, et cetera -- anything not small and manmade. (Note: A manmade lake would also count as "open water," as manmade lakes are too large to be considered controlled environments).
The mouthpiece has this name because it regulates the pressure of the air in the tank. It also delivers the air to the diver.
The diver certification card is casually known as a "C-card." The "C" is (unsurprisingly) for "certification."
There are many risks involved in diving, which some people classify as an extreme sport. However, most risks are avoidable or escapable with a cool head. Panic is the greatest threat to a safe return to surface.
In recreational scuba, among other forms, divers breathe air from their tank only through their mouths. Those making challenging dives -- military divers, for example -- will use a nose-and-mouth setup.
There is also "surface supply" diving. In this mode, a long tube provides air from the surface. You might have seen this in illustrations of 19th-century diving. Scuba is a 20th-century innovation.
A snorkel is a short tube allowing the diver to breathe surface air. It's like a simplified version of surface-supplied air system.
Rebreathers are used in closed-circuit setups, so named because they do not release waste gases (exhalations) into the water. Instead, they recycle exhaled air for partial re-use by the diver. (We say partial because some carbon dioxide must be ejected, as too much is unhealthy).
As mentioned in another question, rebreather systems don't create bubbles, which is an advantage to stealth divers, or underwater photographers who don't want to disturb the environment. However, rebreather systems can also lengthen the time a diver can spend underwater, or let them carry a lighter tank (usually not both at once, as these goals work against each other).
This is one of the first things that new divers learn: Oxygen is actually a minority component of air. Earth's atmosphere is about 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases.
"Gas mixtures" makes it sound very different from air, but bear in mind that air itself is a mixture of gases. Here, we're talking about air that is enriched with other elements, which are beneficial to the diver.
If you knew this one, it was IMMEDIATELY obvious! "Marmite" is a British sandwich spread, like "Vegemite" in Australia.
The "foamed" neoprene used in wetsuits (as opposed to standard neoprene) is very buoyant. So is body fat -- both of these will influence a diver's attempts to achieve negative or neutral buoyancy.
In fact, you'll probably be asked to at least attest to your medical fitness before you can begin scuba training. This isn't an intensive process -- it essentially means you'll sign a form saying you do not have certain disqualifying medical conditions. Later, if you want to be a professional diver or dive instructor, an actual exam will be performed.
Surprised? Asthma was once considered disqualifying, but standards are different today, and asthmatics have proven they can successfully dive. However, the brain conditions listed above are still disqualifiers.
There is evidence that scuba diving poses a risk to the fetus. When can you return to diving? Medically, about four weeks after giving birth is the rule of thumb -- but the sleep deprivation typical of new parents is probably too great a risk to one's judgment!
While all these experiences are valuable in their own ways, military service has been shown to make for clearheaded, competent divers. Obviously, in emergency situations you do have to improvise, but it's not the kind of improv one does on a stage!
Most of the time, if an animal stings or bites you, it's because you have intruded in their environment, and they are frightened. Remember, you're in their home ... so proceed with caution and respect!
Wetsuits are so named because they allow a layer of water to enter the suit; the water absorbs body heat and actually helps keep the diver warm. A "dry suit" does not, providing greater protection in truly frigid waters. Dry suits are expensive and less frequently used than wetsuits.
It is rare for decompression sickness to be so intensive that it affects the lungs. The frequency has decreased in recent decades with improvements in the way breathing gases are used in a dive.
Oxygen: We talk about it like it's completely benign, but it truly is a mixed blessing! Pure oxygen is highly explosive. It also causes oxidative damage to substances from metal to apples (that's why apples brown when exposed to air). And for divers, too high a concentration of oxygen in their air supply can cause nervous-system damage and cell death. Yikes!
"Trimix" is a helium, nitrogen and oxygen mix for diving. Barium is a metal, often used as a contrast agent in medical imaging.
There's such a thing as "nitrogen narcosis," or a feeling of drunkenness and lethargy caused by nitrogen inhalation. This can also lead to bad judgment during a dive. Replacing some of the nitrogen with helium helps.
The National Association of Underwater Instructors is one of the major organizations that certifies divers. It's likely that when you take your test, you'll be expected to live up to standards that, at least in part, NAUI has set.
"Technical diving" is the name for diving that is more than just recreational scuba diving, but isn't professional in purpose (e.g. salvage work). There's no real definition for technical diving, but any of the above complications might qualify.
"BC" is the short form of "buoyancy compensator." It can be any of many pieces of equipment with an air bladder. The air within can be adjusted to help the diver ascend, descend, or stay at depth.