Scuba

To keep their skin looking tight.

220 feet is about 67 metres. The pressure of air at this depth is about 8 bar (or atm). Using standard air the partial pressure (20%) of oxygen is 1.6 bar. This is the boundary where oxygen begins to become toxic and can cause serious health problems (and lead to death).

I am a diver with BSAC and the recommended maximum depth is 50m on air which is about 164 feet.

The alternative is to use other mixes of gas which usually require more advance training but they contain less oxygen so it is safer to diver deeper.

Summary, it is NOT safe to dive to 200ft on standard air

Looks like it is most of the time. One thing to keep in mind is that November is still hurricane season, so if a hurricane is nearby, SCUBA diving is impossible.

It is going to be as safe as any other time going SCUBA diving. One particular month does not make SCUBA diving dangerous. As long as your guide knows what their doing, you will be fine.

It's not recommended for a sport diver to go below 130 feet due to the partial pressure of oxygen being poisonous when it reaches the equivelant of 100% (5 atmospheres as there is about 20% oxygen in the air). Also the effect of Nitrogen narcosis can make your decision making erratic. It's not an exact science as to what depth an individual may succumb to this but 130 feet is a good guage of where you are relatively safe as long as you are obeying all the rules of training and you and your buddy are not irresponsible. Any deeper and you would need to mix gases and should get more specialised training.

just breathe normally through your mouth just keep your head down or it will fill with water! swim on the surface and when you lift you head out of the water makesure that your snorkel has not filled with water before you try to breathe through it again!! have fun ---- I like to "sip" the air over my tongue. It seems to trap droplettes moer effectively. Nice not to aspirate :} Actually, this answer is incorrect. When snorkelling, you take a deep breath, dive down and as u reach the surface u blast the water in the snorkel out and repeat the process. If you are jus swimming on the surface it is not technically snorkelling, but some people like to call it skin diving to clarify. Or -- as you ascend, you can point the snorkel straight back so it's entirely vertical and puff a little air into it at depth. As you ascend, the air in the snorkel will expand, forcing water out. Just as you hit the surface, vigorously rotate your head foprwards and downwards, so the snorkel moves roughly 1890 degrees and the opening is now in the air, nearly vertical. Blast a little air out to remove the tiny amount of water remaining. Also, I think the act of "snorkelling" refers to whatever you choose to do from the time you leave the boat until the time you leave the water. So this would include phases when you're breathing on the surface, diving to depth, holding your breath underwater, clearing your snorkel, etc.

Retired Commodore Ramon Nolasco Baluyot

Actually, 5 ATM can either be 132 feet or 165 feet. We all have 1 ATM above us (the air/sky/atmosphere) that creates a constant pressure.

Sooo.. 1 ATM + 4 ATM (33ft per ATM) = 132 feet underwater. However, if you actually mean 5 ATM UNDERWATER, then it would be 6 ATM (1 ATM + 5 ATM underwater) for the equation which would equal 165 feet.

Hope this helps!

So that the scuba diver could go more streamline in the water.

typically around $20-$30 depending on where you get it done, just ask around for the best price. also check the local fire station, a lot of times they know where to get it done cheap since they have to get tanks hydroed all the time

The Marines have a special kind of SCUBA system (called a re-breather) that recycles the air for them, which prevents the bubbles from being seen from enemy sights. In recreational diving however, we only have a semi-closed re-breather, which partially recycles the air. It does not completely eliminate the bubbles, but it reduces them.

Believe it or not, we can die from too little oxygen AND too much oxygen.

This concept involves partial pressures.

If we first consider using standard air (i.e. 20% Oxygen and 80% Nitrogen):

(1 bar = 1 kilogram of pressure per square centimetre)

At the surface - Total Pressure of air = 1 bar

- Pressure of Oxygen = 0.2 bar

- Pressure of Nitrogen = 0.8 bar

At 10m - Total Pressure of air = 2 bar

- Pressure of Oxygen = 0.4 bar

- Pressure of Nitrogen = 1.6 bar

At 20m - Total Pressure of air = 3 bar

- Pressure of Oxygen = 0.6 bar

- Pressure of Nitrogen = 2.4 bar

At 30m - Total Pressure of air = 4 bar

- Pressure of Oxygen = 0.8 bar

- Pressure of Nitrogen = 3.2 bar

At 40m - Total Pressure of air = 5 bar

- Pressure of Oxygen = 1.0 bar

- Pressure of Nitrogen = 4.0 bar

At 50m - Total Pressure of air = 6 bar

- Pressure of Oxygen = 1.2 bar

- Pressure of Nitrogen = 4.8 bar

At 60m - Total Pressure of air = 7 bar

- Pressure of Oxygen = 1.4 bar

- Pressure of Nitrogen = 5.6 bar

At 70m - Total Pressure of air = 8 bar

- Pressure of Oxygen = 1.6 bar

- Pressure of Nitrogen = 6.4 bar

It is at the partial pressure of 1.6 bar (which occurs at 70m where oxygen becomes toxic. That is why most dive organisations recommend 50m as a maximum for recreational diving.

However, if pure oxygen is used:

At surface - Pressure of Oxygen = 1 bar

At 10m - Pressure of oxygen = 2 bar

The oxygen has already become toxic!

Hope that answers your question. The concept is called "partial pressures" and "oxygen toxicity" if you want to research more on a search engine.

Sea snakes are actually relatively rare creatures. Divers who dive in areas where sea snakes are known to exist (Western Pacific and Indian Ocean) simply take care not to interfere with the animals (which are actually quite docile). Sea snake bites are rare in themselves, and usually happen to paddlers who step accidentally on the snake.

This question is a little vague. To answer in the simplest terms...swim to the surface at a rate of no more than one foot per second. After long dives or deep depths, divers should make a safety stop for several minutes before finally breaking the surface to be certain that the necessary amount of excess nitrogen has been expelled from the body.

The air inside SCUBA tanks is, usually, just regular air that has been compressed and "jammed" into a tank. Some diving applications utilize gas mixtures of oxygen, nitrogen (and sometimes hydrogen).

332 bc

The cartesian diver sinks because the diver wants to get to a place of low pressure

Its alot thicker than regular water and you float alot eaisier. You float eaisier because of the salt content.

If you fly before you dive, then not much (except sometimes you are a bit dehydrated after flying).

However, if you dive before you fly, then bad things can happen. When you dive, your body absorbs nitrogen into your tissues. When you are on the surface after the dive, those gases slowly leave your tissues. However, if you go in an aircraft (especially an unpressurised one), or otherwise ascend to high altitude, the air pressure is much lower, so that gas wants to leave your tissues more quickly, which can form bubbles that lead to decompression sickness.

The risk varies with how deep you have gone, how long you stayed at depth, and how soon afterwards you fly. Most dive agencies recommend that you do not fly for 12 - 24 hours after your last dive. The US Navy recommends a minimum of 4 hours before flying on the assumption that the dive was not a dive involving mandatory decompression stops.
At sea level we all have roughly 15 lbs per square inch of pressure on our bodies (14.7 for the hair-splitters out there). The amount of gas (nitrogen for this explanation) that can and will dissolve in the bodily fluids is related to the amount of pressure applied to the body. For every 33 feet a body is submerged, the atmospheric pressure is doubled. So, for a depth of 33 feet, a diver's body is under 2 atm. 66 feet (often the limit of "Sport diving") that pressure equals to 3 atm. As Boyle's law states, the volume of gas dissolved in solution will double with the square of the pressure. What this means in English is that the more pressure applied to a body, the more gas will dissolve into the liquid. Imagine examining a fresh bottle of Sprite- one sees a clear, colorless liquid with no bubbles. Now crack open that same bottle quickly, and thousands of bubbles form; this is because the pressure on the liquid was released quickly. A diver that goes to a depth absorbs more of the gasses from his or her mix than someone at sea-level. Send that same diver up in a plane soon after diving and his or her blood and lymph behaves like that Sprite; gas bubbles form and cause debilitation pain (the Bends), neurologic or pulmonogic accidents or even death.

Every diver has a different SAC rate (Surface Air Consumption rate). We all breathe in different amounts of air, and have different breathing rates. It also depends on how deep you're talking. Remember, for every 30-33 feet down you go, the pressure reduces the volume in half.

Answer you're probably looking for:

an aluminum 80 cubic foot tank, at about 30 to 50 feet will last me 45 to 60 minutes.

I just noticed the other question at the bottom of this:

The effect of increased water depth on a scuba diver?

Now here's the fun question to answer. Breathing compressed air at depth can be DANGEROUS. Let's say you take a breath of air at 30 feet, and then hold your breath while you come up to the surface (NEVER DO THIS!). The volume of the air in your lungs would double. Odds are your lungs can not hold this much volume, and you can cause your lungs to explode (collapse)

Another effect of breathing air at depth is called "Nitrogen Narcosis". Air is basically 21% oxygen, 79% nitrogen. At the surface ... not a problem. BUT if you're breathing air at depth, the Nitrogen starts messing with you a bit.

The first way is Nitrogen Narcosis. It affects your ability to think. The best way I've ever heard this described is the "Martini Effect". For every 30 feet down you go, it's like having a vodka martini on an empty stomach. So if you're at 120 feet, it's like 4 martinis on an empty stomach. Kinda tipsy.

Now, for the DANGEROUS aspect of Nitrogen at depth. Your lungs take air, and put it into your blood stream. Again, at the surface, this is not a problem. And when you're at depth this isn't necessarily a problem. Where you run into a problem is surfacing. If you come up too fast, or miss your decompression stops which allow you to offgas the nitrogen, nitrogen can form bubbles in your blood stream. The severity of this ranges depending on how deep you are, and how long you were at depth. Scuba divers have computers and dive tables to figure these things out. If you have the nitrogen bubbles forming in your blood stream, it's called "Decompression Illness" or more commonly "The Benz". Treatment can be a range from doing nothing and letting your body to naturally offgas, to having to go into a decompression chamber which puts you back into pressure as if you were at depth and then bring you back slowly. This is of course assuming you survive to get to a hospital with a chamber. Some divers die before they hit the surface. The worst case I've heard of was where they attempted to draw blood from a diver, and the blood had so many bubbles in it ... it was a FOAM. (That diver lost his life before reaching the hospital).

The average adult at rest inhales and exhales something like 7 or 8 liters (about one-fourth of a cubic foot) of air per minute. That totals something like 11,000 liters of air (388 cubic feet) in a day.

because they found better and safer jobs.