How to Use a Snorkel

Using a snorkel properly will give you a clear vision of what's
going on under the sea without having to breathe water.

The Basics
Step1
Test your mask and snorkel together to determine fit and comfort.
Step2
Position the small rubber strap that attaches the snorkel to your mask so that the snorkel passes just above your left ear. (If you are using a special left-handed snorkel, it will be on your right.)
Step3
Take a deep breath, bite down on the mouthpiece and submerge your head in the water.
Step4
Exhale sharply once to clear any water that may be in the snorkel shaft. This is commonly called 'blasting' or 'purging.'
Step5
Inhale gently at first in case there is any residual water. Blast a second time if needed, and continue to do so whenever water enters the snorkel.
Step6
Learn to move gently on the surface'rapid or abrupt movements can fill the snorkel with water.
Step7
Inhale and hold your breath, then dive to explore the underwater environment around you.
Step8
Ascend, make sure the snorkel end is above the surface, then purge to clear the tube of water.
Step9
Breathe cautiously to be sure the snorkel has cleared completely. If you don't have enough air left to purge, lift your head above the surface and take the snorkel out to breathe.
Clearing the Snorkel of Water
Step1
Make sure you are gripping the mouthpiece of the snorkel securely with your teeth.
Step2
Exhale forcefully through your mouth. The majority of the water should be expelled from the tube. This method is commonly called "blasting" or "popping."
Step3
Inhale gently at first in case there is any residual water. Blast a second time if needed.
Step4
Continue blasting whenever water enters the snorkel.
By eHow Sports & Fitness Editor
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Snorkel is ...

A snorkel is a tube around 30 centimeters long and with an inside diameter of between 1.5 and 2.5 centimeters, usually L- or J-shaped and fitted with a mouthpiece at the lower end, and constructed of rubber or plastic. It is used for breathing air from above the water surface when the wearer's mouth and nose are submerged. The snorkel usually has a piece of rubber that attaches the snorkel to the outside of the strap of the diving mask since pushing the snorkel between the mask-strap and the head can cause the mask to leak.

The most common type of snorkel is a simple tube that is allowed to flood when underwater. The snorkeller expels water from the snorkel either with a sharp exhalation on return to the surface (Blast clearing) or by tilting the head backwards right before reaching the surface and exhaling till reaching or "breaking" the surface (Displacement method) and facing forward again (Normal position), before inhaling the next breath. The displacement method expels water by displacing its presence in the snorkel thereby clearing the tube of its contents. A more advance technique that takes practice but one that uses less energy and clears the snorkel with much greater efficiency.

Some modern snorkels have a sump in the mouthpiece to allow a small volume of water to remain in the snorkel without being inhaled when the snorkeller breathes. Some also have a one-way output valve in the sump, which automatically drains the sump as it fills with water. A few snorkels have float-operated valves attached to the top end of the tube to keep water out when the snorkeller submerges, whilst more recent designs have a splash deflector on the top end that directs any water that splashes over the open tube to the outside of the tube, thereby keeping the user's mouth free from water.

Snorkels used to be sold with small "ping pong" balls in a cage mounted to the open end of the tube to prevent water ingress, though these are no longer sold nor recommended to be used since they are considered hazardous to the snorkeller. Similarly, diving masks with a snorkel built into them are considered unsafe and obsolete.

The maximum usable length of the snorkel tube is around 40 centimetres (about 16 inches). A longer tube would place the lungs in deeper water where the surrounding water pressure is higher and the lungs would be unable to inflate when the snorkeller inhales, because the muscles that expand the lungs are not strong enough to operate against the higher pressure. Snorkels also create what is called "dead air space" - when the user takes in a fresh breath, some of the previously exhaled air remains in the snorkel and is recycled into the lungs, reducing breathing efficiency and causing CO2 retention. The greater the volume in the device, the more this problem is exacerbated.

http://en.wikipedia.org/wiki/Snorkeling

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