Introduction
In the previous article of this series we mentioned the mask which is essential for seeing underwater. In this article, we will see the snorkel and wetsuit which are essential so as to breathe and protect ourselves from the cold.

The snorkel
The snorkel is actually a J shaped tube with a mouthpiece. It allows us to be in the water, looking towards the bottom, breathing at the same time. Something very important of course, when searching for something on the sea bottom or looking over your dive buddy.
The width of the snorkel must be at least the same as the trachea. If it is smaller, breathing will be difficult. If it is wider, Co2 will remain inside it when we exhale. Its length must not allow any water to enter. If it is too long, it will again maintain more Co2 than normal.  As far as the question “why don’t we have a long snorkel so as to be truly submerged and breathe at the same time?” is concerned, there are 2 answers. 1st we would not be able to breathe because the difference in pressure between the surface and the depth we are in would make breathing impossible and 2nd such a snorkel would keep all the exhaled air inside and would never actually provide us with “fresh air”.
If water enters into the snorkel, a strong exhaling action will shoot it away. There are also some snorkels with valves that let the water out easily, but they usually start to malfunction after some time. This is why we should prefer simple J designs with a silicone mouthpiece. The width and length are almost the same in all manufacturers, so to avoid writing a whole article about the snorkel, let’s see the next, very important part of our equipment.

The wetsuit
The wetsuit can also be seen as a piece of elastic and heat insulating piece of clothes that is made from the pants and the jacket. It is manufactured from a material called “Neoprene” that is a derivative of oil while there is also neoprene made from a special bed of rock. Imagine the neoprene being the foam that is “cooked” in a large “pan”. When it is cooked, we have what we call a “sheet” of this material. The number of air bubbles in the initial foam is responsible for several characteristics the material will have. Of course its thickness, which is measured in millimeters, also plays an important role. Let’s see these characteristics.

Insulation
Let’s take two 5mm suits. The first one has large air bubbles and the second has smaller ones. The one with the smaller bubbles will inevitably have more neoprene compared to the other wetsuit, which by itself has no insulating characteristics. So we come to the conclusion that the more air bubbles found in a suit, the warmer it will be.

Elasticity
In this case, all of the above also apply here. The larger the air bubbles, the more elastic the material will be since there is more air in the material. That means the wetsuit will be more comfortable, with our movements having less “resistance”.

Endurance at use
Here all of the above are reversed. The softer a material is, the easier it can tear when it comes in contact with the rocks or when we are putting on / taking off the suit.

Endurance at pressure (buoyancy alteration and endurance at use)
Because our suit has air in it, the laws of physics and especially the law of Boyle apply to it. So, as we dive our wetsuit gets compressed. The more air bubbles, the more the suit will get compressed. Consequently, two 5mm suits are 5mm only on the surface. At a depth of X meters, one can be 4mm and the other may have gotten so compressed reaching 3mm. That in its part influences our buoyancy greatly, something we do not really want.
Also, all wetsuits, after extensive use never return to their initial thickness. Due to the constant compression and decompression forced on the suit, our 5mm suit may end up after some time as a 3mm one.
So we come to the conclusion that wetsuits with many air bubbles tend to be more “soft” but also show grater buoyancy alteration and get more easily compressed.

Additaments
Except for all the above, on our initial material that is “simple” neoprene, other layers such as jersey can be added for several reasons.