Contents:
What you need
Basic physics
Techniques
Other
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What you need
The snorkel:
To start snorkel diving, you will need a snorkel (ofc. :biggrin
this is the piece of gear that needs the least attension , we only have two criterias:
Make sure its not to long.
Make sure its not to wide.
A Junior snorkel should not be longer than 30Cm And the diameter of the snorkel no larger than 15mm.
Also the volume should not exceed 1,2dl (do the math!)

For an adult (over 50Kg basically) it should be no longer than 40cm long, 18mm in diameter and have a max volume of 2dl



The reason we have theese measurements is that if it is too big you wont be able to circulate the air, so you will breathe in CO2 (carbondioxide) And then you will pass out.
Tip: If you get an headacke when you dive, your snorkel is most likely too big.
The swimming feet:
This is not something i will use long time with, the most important is that they fit your feet. I can promise you that if they feel uncomfortable over water they will feel like hell after 1h of diving :undecided:
There are two different types of feet, whole and half.

Whole:

With this foot you wont have to use straps in the heel, (this can hurt if you dont use a wet suit)
And it is easyer to get on/off

Half:

With this you will have the ability to tighten the heel, but you cant use them without socks...

There is also some long flippers used for Underwater Hunting (basically really long fins (mine is 90cm) not reccomended for beginners

You will just have to buy 'n try this to find out what you like best, or you could talk to your local diving club.

The mask:
We need to pay a lot of attention to this! becausediving is about watching,expiriencing and enjoying.
Make sure the mask is marked with a sign saying "Tempered" This means that when/if the glass brakes,it will not make pieces wich you can cut yourself on, it just brakes into alot of small dull pieces.
The mask needs to fit your face, if you buy a cheap mask it will probably lack two sealing bits and you will have water in your mask
When you have found a mask that you like, try putting the rubber bands in front of your head, push the mask on and breathe in with your nose, if it falls off while you hold your breath, its not sealed good enough!
Dont give up untill you find a mask that fits!
you get two different types of silicone in your mask, Black and transparent.
USE BLACK! if you have a transparent mask you will get a reflection in the glass, making you see your own eyes, this is very disturbing and it makes it harder too see (ofc).

Black silicone:

Tip: Dont use swimming goggles like theese,

You wont be able to equalize the pressure, and that will cause a "Mask Squeeze". <--- it makes your eyes bleed so dont do it!
Last note: You can get special masks so you wont have to use lenses.

Physics
Arkimedes law: (boyiance (dunno how its written, but you know the thing that makes you go up under water )
This law sound like this: Something lowered down into a liquid gets a boyance equal to the wight of the liquid wich is repressed <- direct translation from norwegian ( the water that gets pused away)

Pressure and volume:
When on the surface the pressure is one "bar".
When we are ten meters down its two "bar"
Twenty meters: 3 Bar and so on
the air in your lungs get compressed as you go down... so at 10 meters (2Bar) you only have half the capacity of what you had on the surface, ill make a diagram here
0m 100% volume 1 bar
10m 1/2 volume 2 Bar
20M 1/3 Volume 3 Bar
30M 1/4 Volume 4 Bar
40m 1/5 Volume 5 Bar
50m 1/6 Volume 6 bar
As a snorkel diver you wont need to worry that much about pressure,as you wont be able to get down to much more than 15-20 meters...
What you need to worry about is the pressure in your ears,and the fact that you get less boyant the longer down you come....
Equalize pressure in your ear: squeeze your nose together with your thump and a fnger, and try top breathe out through the nose, it makes air go into your middle ear and equalize the pressure,
Note: Never do this above water as it will blow your ear :undecided:

Techniques:

Swimming: Just move your feet like if you were crawling(swimming style), and hold your hands infront of you (makes you more aerodynamic )
Diving down:
Not too god pic, but ill try to explain Raise your feet up so you sink down, when your feet are under water, start kicking
Other:
Wetsuit: If it is cold in the water where you live, or you are planning to dive at anything other than the summer, this is highly reccomended,you can get wetsuits in alot of different shapes, styles and thicknesses,

This one is a nice black suit, but you will be hard to see. Also some suits require soap to get into (theese are really warm but really clumsy). Ask you local diving club about what you should get

Harpoons
There is way too many harpoons out there Some are Gas powered some are powered by elastic bands,
You wont need something Gas powered, believe me the rubber bands have enough power

(dont mind the writings ) You wont need a much bigger harpoon than this, it will just get har to load... personally i have a 75Cm long harpoon and it works wonders and believe me, you can shoot through the most