Seeing well means keeping you safe and allowing you to enjoy all that diving has to offer - the colorful plants and fish, the splendid variety, the aspects of our world so interestingly different from the land. To accomplish that, you have to know how to keep your mask clear.

Even well-fitting masks can fog, take in water or even fall off while on a dive. Here's what to do before you go under, and during your undersea adventure to keep your mask in optimal condition.

Obscuring the faceplate glass can happen any one of several ways. Small droplets of water can condense on the interior of the faceplate as a result of sweat off the forehead and the skin from cheekbones. Sometimes there's a small amount of leakage through the mask and the droplets get bounced onto the inside of the glass. But the most common cause is exhalation through the nose of hot, moist air.

When hot, humid air hits the inside of the cold faceplate glass the effect is the same as that of a car windshield on a cold day. It fogs up. Moist, warm air condenses into small droplets and visual acuity is decreased.

Scuba Gear

The old saying 'an ounce of prevention is worth a pound of cure' is worth remembering here.

Before you submerge, coat the interior of the faceplate with a thin layer of material that will disperse the droplets as they start to form. That material can be anti-fogging spray from a commercial dive shop. Or, it could be any one of several home recipes developed by experienced divers over decades.

Raw potatoes have a starchy liquid that works well, for example. Cut a potato in quarters and smear the flat surface over the glass just before going under. Then rinse the mask lightly and put it on. Don't have any potatoes? Try baby shampoo or some other tearless shampoo. Squirt a tiny amount on two fingers and spread it around, then rinse, but not enough to wash it off.

As a last resort, spit will do. The drawback is that spit isn't most individuals' idea of something pleasant to have close to the eyes. It also tends to attract bacteria and washes off too easily. But, it's better than nothing.

Once you're under, if a small amount of moisture gets into the mask through the boundary (the skirt edge) that too can be dealt with easily. Here are some easy to follow tips.

As you sense water enter the mask, inhale through the mouth and - though it isn't the standard breathing technique - exhale sharply through the nose. Some divers will tilt the bottom of the mask out slightly AT THE SAME TIME as they exhale. That's tricky and can result in letting even more water in. Usually a good snort will clear the mask.

Repeat as needed. If your mask fogs, but you've prepared it as above, it should clear in a few seconds. As a last resort, you can surface and take care of the problem, but that costs dive time that most scuba enthusiasts won't want to sacrifice.

Be sure to keep your mask clear as much as possible. Your safety depends on being able to judge potential dangers underwater. It also allows you to see everything you took all the trouble to go down to experience.

Swim fins (Mares)

There's a lot that goes into engineering a great fin. Here are some guidelines for novice divers to help make it easier to choose.

Like shoes, fins have to fit well in order to be comfortable and function properly. Unlike shoes, you don't generally wear socks to help adjust the fit and you aren't usually somewhere you can change to another pair if yours aren't right. So make an effort to get it right the first time.

Wash your feet and try on several pair, making sure there's no sand or dirt on your feet during the trial. Sit on the bench and flip the fins up and down. The air won't offer the same resistance as water, but moving your leg and ankle around will give you an initial impression.

The fins need to be snug and seal well around the foot and for full fins the ankle. Snug, not crushing. Fins that are too tight will impair movement. Fins that are too loose will scrape the skin along the edge and within the boot. Sore feet shorten dives.

Fins have to be stiff enough to provide good thrust, but flexible enough to not wear out the leg muscles too quickly. Getting that balance right is a never-ending challenge for designers and divers, since every fin and diver are unique.

One relatively recent approach to that problem has been the development of split fin styles. The traditional fin is a large continuous web about 16 inches long and eight inches wide at the tip though length and width variations are common and sometimes extreme. Split fins often have similar dimensions but add a space up the middle of the fin.

Split fins make it possible for the diver to produce thrust with less effort, though they can reduce maneuverability. Turning is slower with some designs. So, for those underwater photographers who need to rotate quickly to snap that elusive fish, you'll want to bring two pair - one traditional, one split - and compare.

One factor novices frequently fail to take into account when purchasing fins is buoyancy. Since they're selected in air, you tend to forget about that. But buoyancy is an important issue in diving. Divers try to remain close to neutral buoyancy in order to reduce the fatigue of descending and ascending.

Many fins are designed to float so that if they fall off they can be more easily retrieved at the surface. But, fins that are constantly pulling your feet up make maintaining neutral buoyancy difficult.

Positively buoyant fins can be balanced out with ankle weights, but that's one more piece of equipment to buy, haul and strap on. Not fun. Try to get info on the degree of buoyancy when researching your purchase.

Last, consider whether you want full fitting fins that rise up over the ankle, what sort of insert you want (booty or not), and whether a quick release clasp or regular heel strap is desired. All these convenience and comfort factors can help push you to one model versus another.

Buddy Commando jacket

Many designs today will provide straps and padding for integrating the tank with the buoyancy compensator. Some will even have integrated regulators and hose assemblies. The specific size and shape will determine, among other things, where the tank rides on the back. A low-slung tank can be a literal pain in the butt.

Some will make the tank ride higher. That keeps pressure off the base of the spine and makes for a more comfortable dive with less chance of bruising. Backpackers will be familiar with the principle that having the pack higher on the back up to a point makes for an easier haul.

Some wing styles will even have an integrated steel backplate, which makes carrying a tank easier, but adds weight.

Traditional buoyancy compensators have an inflator/deflator over the left shoulder. But not everyone is right handed. And, not everyone has long arms, making using the device difficult. Several new designs have the inflator lower on the chest to allow for easy reach, and some can be found on the right side.

A buoyancy compensator can be inflated using a separate tank - in days past even carbon dioxide was used rather than air. But, nowadays, filling the buoyancy compensator from the diver's main air tank is the most common method. As a result, several have special valves which allow for breathing from the bladders in the jacket during an emergency.

Newer designs often come with handy extra pockets to store items taken down or picked up during the dive. Some are large enough to carry an extra mask.

Others have D-rings that allow the attachment of ropes that can be used to haul up a diver or tie a tether between buddies. D-rings can be used to attach extra gear you may want to take down during the dive. Bags to haul up shells and other finds from the deep can be attached to the jacket using the D-rings.

Special 'travel buoyancy compensators' are made especially lightweight, but often have only very basic features. One optional feature which helps the travel aspect is the use of an integrated alternate inflator/regulator. These make a separate emergency regulator (an 'octopus') unnecessary and allows the diver to have a spare while still controlling buoyancy.

Heavier-duty styles will usually offer the option to add weights to a wing-style buoyancy compensator in order to compensate for the tendency to force a diver onto his or her face at the surface. Weight systems are often made up of special pockets that can be added or removed as desired.

Look for a buoyancy compensator with plenty of dump valves, usually located on the rear right shoulder or the rear left hip. Most will have at least two. These allow for easier deflation, but you should still be able to operate them with your eyes closed.

Buoyancy compensator

'Positive buoyancy' causes the diver to rise, 'negative buoyancy' results in sinking.

Thanks to modern materials science and great product design, buoyancy compensators are better than ever. They come in a variety of styles, sizes and materials - not to mention price range - and have a dozen different built-in helpful devices.

Buoyancy compensators come in three basic styles: wings, jackets or vests.

Wing buoyancy compensators are thinner, lighter-weight wrap-ons that have bladders to trap air filled usually from the main tank. They are easy to travel with and provide good lift.

Full jacket buoyancy compensators allow for larger air pockets, providing substantial lift to heavier divers or those who carry more weight, such as an extra tank or rocks off the bottom.

Vests are the traditional design familiar from WWII movies and look like what most would think of as a 'life vest'. The style is sometimes called a horse collar or adjustable buoyancy life jacket (ABLJ).

The traditional life vest style can be bulky and uncomfortable, since the majority of the jacket is in the front. When inflated it can decrease the freedom of head and arm movement and bump up against anything being examined closely. But it has one major advantage: when a diver floats to the surface in the ABLJ he or she will tend to be forced onto the back.

Most contemporary designs move the diver onto his or her face. If you surface normally that's not usually a problem. It takes little effort to compensate by using fins and balance to remain upright.

But, an unconscious diver floating on his or her back is much more likely to survive at the surface. If there's no one around to immediately lift them out of the water, or force the diver over, being face down can be fatal within minutes.

Like any sports clothing a buoyancy compensator will need to be tested for fit, since every diver's body is a little bit different. Some are longer, riding closer to the thighs, others shorter and even above the hip.

The shorter styles are particularly useful for women, who tend to have shorter backs than men. Also, the shorter vest helps avoid being bruised in the hips by any integrated weights near the base of the buoyancy compensator. Some styles allow the integrated weights to be quick-released in an emergency.

They come in a wide range of sizes, but be sure to allow for the thickness of the wetsuit or drysuit. A man with a 40 inch chest would probably want a jacket at least 42 inches.

Denier count is important. Denier is a measure of the thread thickness used in the weave of the jacket. A higher denier buoyancy compensator (such as 1,200) will resist scrapes and tears better, but a lower count (400) will be more puncture-proof.

Low denier jackets are lighter weight and so are easier to pack and carry, but a higher denier jacket will tend to wear longer. Some buoyancy compensators have layers with different counts to get the best of both features.

When you glance at your partner, he or she and you both should already be well familiar with common dive signals. Even as few as a half-dozen well-practiced signals that you can recognize underwater can save a life. All of them should be practiced in advance and immediately after diving under the surface to confirm visibility. Obviously, you should make clear to each partner that it is just a practice drill.

At the surface, if you get into trouble, raise and extend an arm and wave it up and down as if ready to slice the water. That signals you have an emergency and need help. Those on the boat should be watching at all times for just such an occurrence.

Under the water there are a number of signals used to indicate trouble. One is to simply point to the head and shake your head in a common 'No'. That could indicate a problem with the air supply, for example. If that's the trouble use the following to suggest buddy breathing. Lift your arm and bend at the elbow. Point a finger across your chest and move it back and forth.

For external dangers, extend your arm and point a finger, shaking your head no. Be sure not to confuse this with an ordinary expression of desire to show something interesting under the water. That should not involve head shaking.

If you experience excessive cold it can cause serious damage within a few minutes. In extreme cases, nerve damage to hands and feet can be permanent. Before things reach this level, fold your arms, make fists and imitate a broad shiver. You should surface as quickly as safety allows.

That ascension can be signaled by holding a fist at shoulder level and extending a thumb upward, then wave the fist upward. Take care though not to rise too fast when you can avoid it. You may start to feel the effects of nitrogen narcosis. If you do, point your finger toward your head and wave it around in the classic "He's crazy" fashion.

When all is safe and you want to descend, simply reverse the ascension signal by making a fist at shoulder height and point the thumb down. Wave it downward a few times. Before you start to go, you may want to join your partner, so give the 'buddy up' sign. Extend your hand and put the index and middle finger together, like the Cub Scout sign.

When everything is ok, you can signal so by using the classic sign. Just make a circle with your thumb and index finger, with the other three fingers together and straight. In some cases, this is posing a question: "Are you OK?" Agree in advance on the meaning. In this case, you can use the same thumb and finger circle, with the other three fingers circled too, to answer "Yes, I'm OK."

On the surface, you can use one arm circled and touching the head to signal OK. If you have both arms free make the circle by touching the tips of the fingers together over your head.

Learning these simple signals can keep you and your partners safer underwater. That increases the odds that you'll be able to enjoy a dive a second time.

Scuba Diving - Learning To Equalize

Early in those lessons is one which covers how to handle the effects of pressure.

Water pressure compresses gas much more readily than liquid. As a result, your torso and arms and legs may feel only slight squeezing, but any part of the body that contains trapped air will experience a much greater net force.

The ears are a prime example. As you enter the water, a small amount of air is invariably trapped in the ear. Water quickly fills the canal, but the ear drum - up to a point - is impenetrable. Air behind the drum surface gets squeezed, as if you were pressing on an orchestra drum. With nowhere to go, as the volume is decreased the pressure increases.

That's an instance of a physics principle called Boyle's Law, taught in all elementary scuba diving courses. All you want to do is get in the water and you get sent back to science class!

Boyle's Law states PV = constant (for a given temperature).

That may look scary, but it's really very simple. Measure the pressure and volume and multiply them together. As you increase one the other goes down, to keep the final product constant. For example, if you squeeze a balloon, you're decreasing the volume. The pressure inside goes up. That's why if you let go it returns to normal. Halve the volume and the pressure doubles.

As the volume of air behind the ear drum is lowered, the pressure inside goes up. At a certain point, that can cause discomfort and ultimately serious ear damage. But taking care of the problem is also elementary.

Descend into the water. As you feel the pressure on your inner ear, pinch or hold your nose and swallow or blow gently against your closed nose. Swallowing moves air from the ear canal into other cavities where the volume is much greater and the small change isn't noticed. Most of your body's air system is connected in one way or another.

Repeat as needed as you descend. The water pressure will increase by 1 atm (one atmosphere) for every 33 feet (10 m) you descend, and any air still trapped will continue to be squeezed. Once the pressure inside equals that outside, you'll no longer feel the discomfort.

Several factors can affect the severity of the pressure.

Colds and other sinus problems can hinder the ability to move air around the system. It's best to avoid diving under those conditions. Allergies, too, obviously play hell with your sinuses. But, beware of diving after taking any allergy medicine that can make you drowsy. Safe diving requires acute mental focus.

Don't wait until your ears feel an uncomfortable amount of pressure before equalizing. Make it a habit to perform the technique as you descend and ascend, whether you feel the need to or not.

There are other areas, too, that trap air. Your face mask for example.

As you descend, your face mask is subject to the same pressure. The glass plate is rigid, so it resists well. But, the pressure on the skirt (the 'rubber part') of your face mask will experience additional pressure and compress the air in front of your eyes slightly.

A good mask will counteract that, but you can help it along by slight exhalations through the nose when needed. Do so slowly, to avoid fogging the mask, though.

Equalizing the pressure in other cavities that trap air, such as the lungs, is taken care of automatically by the regulator.

Equalizing air pressure as you dive will help you stay safe and allow you to enjoy your dive to the fullest.

NAUI logo

Certification is the process of obtaining a certificate from a recognized diving school with authorized instructors. It's the result of taking courses that teach scuba diving. Simple. Deciding whether you will want to invest the time and money to get certified is a little less so.

Professional Association of Diving Instructors

The two major diver training organizations are NAUI (National Association of Underwater Instructors) and PADI (Professional Association of Diving Instructors). Both have been in existence for decades and have approved facilities across the country.

NAUI was founded in 1959 and held its first Instructor Certification course in 1960. Those instructors then went on to teach others, who became instructors, and so on to the present day. Jacques Cousteau was at one time on the Board of Advisors, as have been many celebrities - such as Lloyd Bridges of early TV's Sea Hunt fame - and divers renowned in the scuba diving world.

But what's important is not the names that NAUI advertisements can display, but the quality of instruction in NAUI-certified schools. And, like any large organization, these vary. For the most part schools have highly qualified instructors with thousands of hours of real-life underwater experience.

On top of real diving experience, NAUI instructors themselves have attended and passed an array of courses. Those courses cover the breadth of diving - recreational, sport, technical… you name it. Instructors will acquire knowledge in the physics and physiology of underwater diving, equipment and its use, safety and all the other topics essential to good diving.

Instructions for students is a combination of self-study, classroom theory and practical guidance in pools and open water areas. Courses are offered at every level from absolute beginner to advanced technical diving of the sort U.S. Navy Seals receive.

Occasionally someone will hang up a shingle advertising themselves as a 'qualified instructor'. But only NAUI-certified instructors are authorized to display or use in advertising the fact that they are NAUI certified.

Ditto for PADI-certified courses and instructors. PADI members teach the majority of recreational divers and issue almost a million certificates per year.

If you plan to take a class look for that, at minimum.

Anyone who 'just wants to get into the water' can do that. There are no laws against it. Although some dive shops won't fill your tanks without seeing a certificate. But no one can stop you from committing suicide either though, oddly, there are laws against that in some jurisdictions.

Consider carefully whether you can experience a safe, enjoyable dive without some instruction. Diving is risky, even in lakes or smaller bodies of water. The risks of nitrogen narcosis, decompression sickness - not to mention the potential for unfriendly creatures or conditions underwater - and a host of other dangers are real and even likely to those who venture out without guidance.

At minimum, a novice diver should have an experienced buddy who can and will explain at least enough to minimize the risk of serious injury or worse. After all, you're not born knowing that it isn't safe to ascend from a 50-foot dive faster than 30 feet per minute.

It's your life and it's irreplaceable. Getting some instruction is well worth the few hours and a few hundred dollars it will cost you. Certification is good for life and good for your life.

Dive computer logbook

Workers spent long hours in caissons, compressed-air filled chambers underwater near the supports of the bridge. When they surfaced, they experienced joint pain, abdominal cramps and sometimes death. The condition came to be known as 'caissons disease'.

In the case of scuba diving, the cause is now fairly well understood. Nitrogen in the air breathed from the tank dissolves into the blood as the diver descends. As the diver ascends, that nitrogen comes out of the blood as a result of the lowered pressure. It forms small bubbles that can grow larger unless re-absorbed into the blood stream or exhaled out through the lungs.

When enough of those bubbles get to a certain volume, the results are the well-known symptoms of decompression sickness.

Technically, the phenomenon is an instance of a principle of physics known as Henry's Law, which is taught in all basic diving courses. It's similar to what happens when a soda can is popped. The rapid change in pressure causes dissolved gases to bubble out of the liquid. How much gas dissolves, and how quickly it is released later depends on the pressure at each point in the dive.

Permanent health impairment can result, even when the diver survives. DCS is nothing to toy around with, and so avoiding it is one of the first lessons a novice diver has to learn. Fortunately, that's very easy with the help of dive tables or a dive computer or even a diving watch.

As the diver ascends, time is allowed for remaining neutrally buoyant - neither sinking nor floating - at several levels on the way up. How long to spend at each stop depends on the specific way the diver descended, but on average it amounts to spending from one to three minutes at each 30 feet (9 m) on the way up.

For short dives, divers can rise continuously provided they don't ascend quicker than about 30 feet (10 m) per minute for any dive deeper than 20 feet (6 m). Even then a safety stop at 10 to 20 feet (3 to 6 meters) is often performed.

Deeper dives require more stops of longer duration, especially if the diver didn't spend most of the dive time at one depth. There are other factors, such as age and general physical condition, body type (fat stores nitrogen more effectively), the temperature before and during the dive and others.

The rate of ascent and number of stops changes when the tank air contains a different mix of nitrogen, oxygen and helium. All that complexity can be programmed into a dive computer - a small wristwatch that monitors the dive and calculates a safe rate of ascent and length of stops.

That makes them much more useful than the older method, which relied on tables printed on plastic-laminated cards or simply experience. But, both those methods are still in use.

Dive tables, though, are only partially reliable since they typically assume what's called a 'square dive', in which the diver descends more or less straight down, then stays at one constant depth before ascending.

Since the result can be so serious, investing in a good dive computer is money well spent. Using it and following good diving practice taught by a skilled instructor, is the best way to prevent ruining a vacation and maybe all the ones to come.

Watertight housing Canon WP-DC600 for IXUS v2

Before buying any equipment, every diver should memorize and practice hand signals with his or her diving partners. Equipment can malfunction, underwater obstructions can reduce their effectiveness and the old-fashioned methods remain cheap and reliable. But if you can afford it, adding the benefits offered by today's technology can increase the safety of your dive by optimizing your communication.

You could buy a simple, yet effective dive slate. These are underwater 'chalkboards' that can be hung around the neck or tied to a belt. They come with a pen capable of writing under the water. You won't want to write a novel, but a few choice words at the right time can be an immense help.

There are underwater phones with microphones and receivers that allow communication between dive buddies. They're a bit pricey, but there are models that integrate into your face mask or with just the regulator.

Their range is fully adequate for any distance you need (50 to 500 meters). You should never be farther away than that from your buddy anyway. Battery life is 8 to 10 hours, so they'll last through multiple dives.

FFMs (Full Face Masks) offer a number of different radio-style communication options. Range varies, but it's more than adequate to any normal diving situation. They make great options for situations where an experienced diver is attempting to guide a novice.

The instructor can offer helpful advice in real-time and the novice gains an extra degree of comfort from being able to hear as well as see. They're especially helpful for those minimum visibility situations.

There are even underwater video cameras and computers that can supplement your options.

If you're looking to do some underwater photography or research, these can be indispensable. Some of the video gear is little more than a waterproof wrapper for your camcorder. Others are a fully integrated unit.

Wireless, underwater laptops can be used to record sights, process video from the camera or signal your dive partner. That's the ultimate in high-tech diving!

When an object underwater rises, it's positively buoyant. If it sinks, it's negatively buoyant. When it remains stationary, divers say it has achieved 'neutral buoyancy' - the goal for all divers.

The purpose of diving is to enjoy investigating the undersea world so different from dry land. That's difficult if you're constantly sinking or rising. Neutral buoyancy allows a diver to control the dive and move around freely. Hence, divers are taught early on in scuba diving courses several methods for maintaining neutral buoyancy.

In principle, the method used by buoyancy compensators is simple.

A buoyancy compensator works by filling bladders in the device with air. Since air is less dense than water, it's positively buoyant. The attached jacket forces the diver up. All other things being equal the more air, the more upward force.

But not all things are equal. As the diver rises, the pressure decreases, expanding the volume of the air in accordance with Boyle's law (Pressure x Volume = a constant, at a given temperature). Similarly, as the diver sinks the pressure on the jacket increases, lowering the volume of air it contains. That reduced volume causes the buoyant force upward to lessen, leading to an even faster descent.

By inflating or deflating the buoyancy compensator, the diver can control how much or how little buoyant force it provides. Working alongside (or with some designs, inside) the buoyancy compensator are weights that counteract the buoyancy.

Weight belts are often used around the waist and/or ankles to maintain the desired level of buoyancy. The ankle weights are used to compensate for positively buoyant fins. In many contemporary designs, the weights will be integrated into the jacket, but in such a way that they can be quickly released during an emergency.

Balancing out all those forces to maintain neutral buoyancy is a dynamic process for both the jacket and the diver. Part of diver training in any scuba diving certification course will involve education in how to deal with those inescapable physical facts.

Beyond making a dive convenient and pleasant, buoyancy compensators have a safety function. A diver that loses motor function or consciousness can be floated safely to the surface using the buoyancy compensator alone.

Using the buoyancy compensator properly is imperative, though, in order to avoid two potential problems. (1) Rising to the surface too quickly can produce decompression sickness. (2) Even once the diver reaches the surface it's possible to drown if the buoyancy compensator faces the diver down rather than up, as many contemporary styles do.

Divers should always dive with a buddy and preferably with at least one topside observer in the boat. Anyone who bobs to the surface can then be quickly retrieved and administered first aid, if necessary.