Safe Surfacing Methods for Deep Sea Girls

Hello, I love Vocaloid. Vocaloid is great.

Deep Sea Girl

It is a masterpiece.

The song concludes with the Deep Sea Girl, who 'found that person who captured her heart,' finally surfacing, ending on a note that evokes hope.

Is she really going to be okay?

I have heard that the time when your mental state is starting to recover is actually when you are most unstable.

I became so worried that I couldn't sleep at night, so I...

I got my scuba diving certification.

Learning Scuba Diving with a Deep Sea Girl

In drift diving, where the boat is not moored and you enter and exit the water at different points, you need to be picked up by the boat after surfacing. In such cases, if you have no markers, you will be swept away by the waves and lost.
For times like these, we carry a fluorescent-colored flotation device called a signal float.

Even if you are not drift diving, you should use a float for rescue if an emergency occurs, such as getting separated from your diving buddy or surfacing alone. In other words, it is best to carry one for any type of diving.

In places with little current, such as inlets in the summer, the water near the surface warmed by the sun and the cold water in the depths do not mix, and the temperature can change rapidly depending on the depth. Also, the temperature can change suddenly in vertical directions, such as in the shadows of rocks. This layer of water caused by temperature differences is called a thermocline.
The deep sea girl must have passed through a thermocline as she sank. Before that, she says, "Where am I headed, and what should I do? A single ray of light suddenly shines through," so she might have been in a place with many rock shadows.

Sudden temperature changes can drain your energy and pose risks such as hypothermia. It is important to get a lecture on the dive site from local diving shop staff who know the spot well.

When you go diving, you encounter very beautiful sea creatures.

However, sea creatures (the person who captivates my heart) are very delicate. You must not startle them carelessly or touch them recklessly. Also, there are many dangerous creatures in the sea. There are dangers such as "cuts from coral, barnacles, etc., bite wounds from octopuses, moray eels, etc., as well as sting wounds from cone snails, long-spined sea urchins, etc." (← This wording is frequently asked on the diver certification exam).
For your own sake and for the sake of the sea, let's watch over them gently.

When swimming while diving, you need to be conscious of neutral buoyancy. Neutral buoyancy is a state where buoyancy and gravity are balanced, resulting in a condition close to weightlessness. In this state, by swimming without fighting the water current and moving your fins (wings of freedom) widely and slowly, you can enjoy diving freely without exhausting your stamina.
I am a novice who just started this year, so I am not yet good at maintaining neutral buoyancy and swimming without flailing. I want to gain more experience and enjoy diving gracefully enough to be admired by a deep sea girl.

When diving, it is usually called a buddy system, and you dive with multiple people. You must not go far away alone. From the tank, there is usually the regulator you use yourself and a breathing apparatus (called an octopus) to share air if your buddy has an emergency. The distance you are allowed to be from your buddy is "the distance you can approach your buddy while exhaling when you suddenly cannot breathe, and grab the octopus." A deep sea girl who has approached close enough that "our eyes met while I was watching" can be said to be exemplary.

Underwater, red light with long wavelengths is easily absorbed, while blue light with short wavelengths is not easily absorbed. This is why the sea is blue.
Underwater, colors are visible in the order of orange, white, and yellow. The deep sea girl's cheeks must have looked orange. How cute.
Also, when looking through a mask underwater, things feel closer and larger than they actually are.

Diving can be done by obtaining a private license, but if you want to work in a specialized diving profession such as at an aquarium or a rescue team, you need to obtain a national qualification called a "Diver." How light and sound are perceived underwater is frequently asked in this diver exam.
- Red is easily absorbed, while orange, white, and yellow are easy to see
- Sound travels faster and longer than in the air, so you cannot tell which direction the sound came from
Remember these as a set.

If you get separated from your buddy, it is an emergency, so you must not continue diving. First, search for your buddy underwater for one minute. If you still cannot find them, surface to the water. After surfacing, signal your location using a signal float or similar.
When the buddy also notices that their partner is missing, they should immediately stop the planned dive to search for their partner, and if they cannot be found, they should surface.

In diving, the remaining amount of air in the tank (residual pressure) equals activity time. You must check the residual pressure frequently and dive with a margin.
However, what should you do if some kind of emergency occurs and you are about to run out of air? When a buddy is nearby, you surface safely while receiving air from the emergency octopus.

However, in this case, the deep sea girl has become separated from her buddy. In such a situation, if the water is sufficiently shallow (around 9m), you perform a "Controlled Emergency Swimming Ascent (CESA)."
This is a method where you look up, keep the regulator in your mouth, and swim toward the surface at a normal ascent rate (18m per minute or less) without dropping your weights. You must never hold your breath during this. If you hold your breath, the air inside your lungs, which was compressed by water pressure, will expand and damage your lungs, leading to fatal injuries. For this reason, you should ascend while saying "ahhhh" to keep exhaling.

That is correct. During an emergency ascent, you raise one arm above your head to ensure safety above you while ascending.

By the way, if you run out of air at a depth greater than 9m and your buddy is not nearby, you perform an "emergency ascent." In this case, you drop your weights and ascend as slowly as possible. If your ascent rate becomes too high, the risk of the aforementioned lung lacerations or decompression sickness increases, but since it is an emergency, it is still better than the alternative if you can make it to the surface.

Diving is always accompanied by the risk of "decompression sickness." In diving, because you breathe compressed air while underwater under pressure, nitrogen dissolves into your blood at high pressure. It is the same as how carbonated water dissolves carbon dioxide in water under high pressure. When the pressure drops due to a rapid ascent or similar, it turns into gas from the blood, as if opening a carbonated drink, which can damage blood vessels, nerves, and joints. This is decompression sickness.

To prevent decompression sickness, it is important to ascend slowly. Usually, you ascend at 18m per minute or less, which is generally slower than the small bubbles rising. Also, depending on how deep and for how long you were diving, you set a "decompression time" where you wait for a certain period at specific depths while gradually ascending.
There are also times when you limit your dive time so that you do not need to set a decompression time at all. This no-decompression limit can be easily checked using a table called a "dive table."

That said, even when you are within the no-decompression limit, there is still a risk of decompression sickness, so for further prevention, you stay at a depth of around 5m for a certain period. This is called a "safety stop."
Also, a dive table can only be checked based on the maximum depth underwater and cannot account for changes in depth. Therefore, you wear a wristwatch-style device called a dive computer, which measures the time spent underwater and changes in depth, and the computer automatically tells you the appropriate stop time. By following this, you can enjoy safe diving.

If "taking flight" means finishing a dive in places like Okinawa and returning by airplane, you need to be careful. When you go up into the sky in an airplane, the air pressure drops even lower than on the ground. This means there is a possibility that the nitrogen dissolved in your blood will turn into gas, posing a risk of decompression sickness. If you have done multiple dives in one day, you must not board an airplane for at least 18 hours. Of course, you should also avoid activities involving rapid changes in air pressure, such as mountain climbing.

Note that the deep sea girl is free-diving. Basically, decompression sickness does not occur with free-diving at the level of an average person. However, long-duration, multiple-dive, and deep-depth free-diving at the level of a professional diver (ama) seems to carry a risk of decompression sickness. Also, there are individual differences in susceptibility to decompression sickness, and it can happen even if you strictly follow the rules. If you feel any abnormalities in your body, consult a medical institution.

...So, this was just an article where I wanted to write down what I learned since I started diving as a hobby. Sorry.

I am a beginner, so I am sorry if I got anything wrong... please teach me.

See you next time in "The Deep Sea Girl Gets Her Diver Certification."

Well then, have a great Vocaloid & diving life!

This article is participating in the Vocaloid Listener Advent Calendar. Thank you every year, obscure.!

Bonus

In the sea of sorrow

A sunken scrubbing brush

Location: Kita Daito Island
(The sea in Okinawa is too beautiful to feel like a sea of sorrow, isn't it?)