Many swimmers often wonder, is it possible to be underwater without glasses? In order to answer this difficult question, it is necessary to take into account what kind of water it is: sea or from the water supply? Of course, if the water contains impurities that are harmful to the eyes, for example, a high content of chlorine, then it is better to use special goggles for swimming.

Can you open your eyes in tap water?

Tap water is disinfected by chlorination, so chlorine is present in small quantities. If you swim in such water without goggles, if it comes into contact with the eyes, some people who are sensitive to chlorine may experience reactive conjunctivitis or irritation.

In the event that pathogenic bacteria enter the water due to the deterioration of water pipes and an insufficient degree of disinfection, they can cause inflammatory eye diseases. That is why it is not recommended to be under water with your eyes open, but tap water is quite suitable for washing.

Chlorinated pool water

As a rule, the same tap water is used in pools, but with a high content of chlorine. Due to the high concentration of this substance, it is impossible to open your eyes underwater.

There may also be bacteria that are not sensitive to chlorine. Contact with such water on the mucous membrane of the eyes can lead to the development of reactive conjunctivitis and other inflammatory diseases. That is why, when going to the pool, do not forget to take your glasses with you.

Sea water

The seas have different concentrations of salt. For example, in the Black and Baltic Seas, this indicator is suitable for diving with open eyes. The person will not experience any discomfort. If there is a high concentration of salt in the sea, then it is better to use special goggles for swimming. Otherwise, burning and tingling in the eyes may occur.

The human eye is not adapted for prolonged contact with the aquatic environment, whether it be tap water or river water. From prolonged contact with water, the eye loses the protective layer of the tear film, after which the process of inflammation of the cornea may begin. In general, it is not dangerous if contact with water is not too long.

Rivers and freshwater reservoirs

As a rule, freshwater contains a high concentration of pathogenic microorganisms. Even ordinary bathing in such conditions is associated with a high risk of infection. In addition, the water in freshwater reservoirs is usually cloudy, so few people have the desire to open their eyes when diving. Of course, there are clean rivers and reservoirs, but they, as a rule, are not located within the city, it takes a very long time to get to them.

Contact lenses

People who are forced to wear contact lenses should definitely remove them while swimming. If a person dives with his eyes open, they will simply be washed away with water and then you will have to buy new lenses. It is better to wear special goggles for swimming and then you can dive for your own pleasure and admire the underwater landscape.

People tend to show a lot of curiosity to find out what's going on underwater. When all the oceans were explored and mapped, the explorers turned their eyes to their depths and began to sink deeper and deeper. Any person sometimes wants to open his eyes under water, even in a simple pool, when he knows perfectly well that his eyes will pinch because of chlorine. However, there are some ways to get used to the discomfort experienced, but there are also quite reasonable precautions, as trying to see the underwater world with the naked eye can lead to unpleasant consequences for vision. Wherever you are, in the pool, at the sea or in the lake, to satisfy your natural curiosity and look under the water column, it is usually recommended to use special goggles or a mask for swimming.

Steps

Naked vision underwater

Underwater vision in the pool. Looking underwater seems easy, but anyone who has done it in a pool of heavily chlorinated water knows how it burns their eyes. Fortunately, with the help of a number of tricks, you can adjust your earthly eyes to water. If these techniques do not work for you, then for safe underwater vision in the pool, it is recommended to resort to the use of glasses or a swimming mask.

Underwater vision in the ocean. Swimming in a natural water pool will not irritate your eyes due to chlorine, but since the water will not contain chlorine, it will contain a wide variety of bacteria and contaminants. Near the coastline, waves constantly raise sand and small stones from the bottom, which creates the possibility of scratching the cornea of ​​\u200b\u200bthe eye. However, sailing away from the coast may be more suitable for looking underwater.

Underwater vision in the lake. In a freshwater lake, the main danger to the eyes is bacteria. While you might not necessarily get in trouble for contact with single-celled lake dwellers, it's wiser to use eye protection (goggles or a swim mask) if you want to take a look at the underwater world. In addition, when swimming in shallow areas of the lake, you yourself can pick up dirt and sand from the bottom, which can damage unprotected eyes.

Don't forget to remove your contact lenses. In any of the above situations, contact lenses must first be removed. While there is some risk of simply losing the lenses (although the water pressure should hold them in place), the greater danger is the possibility of a bacterial infection on the lenses.

• If you wear glasses or contact lenses to improve your vision, you can order a swimming mask to be made according to the appropriate prescription. With it, you will be noticeably safer to swim than trying to see the underwater world with the naked eye. This option is suitable for all those who already do not see very well without glasses.

The use of aids

1. Put on your goggles. Goggles will allow you to see well underwater and prevent eye irritation. The glasses are securely fixed on the head with an elastic band. Putting on glasses is very simple: first put the lenses on your eyes, and then pull the elastic band from the glasses over your head. The elastic should be snug against the top of your head, but not too tight to cause discomfort.

   Use a swimming mask. A swimming mask provides the swimmer with additional protection, as it not only protects the eyes, but also pinches the nose. If you feel uncomfortable when air comes out through your nose underwater, then with a mask you no longer have to pinch your nose with your hand! Like glasses, the mask is fixed on the head with a rubber strap (only wider). You should be able to swim underwater without having to press the mask against your face.

   Consider scuba diving. Scuba diving is diving under water using oxygen cylinders (or cylinders with a special gas mixture) for breathing. Divers equip themselves with masks, wetsuits, fins and buoyancy compensators to navigate as safely as possible underwater and explore the seabed, reefs, caves and shipwrecks. If you are interested in diving, look for appropriate training courses nearby! In this activity, there are some nuances that need to be learned in order to minimize the risks associated with moving underwater, as people are not adapted to this environment.

What could be more beautiful than cutting through the expanses of water, admiring the marine flora and fauna. However, for this you need to be able to swim. And not just swim, but swim underwater – confidently and gracefully. Some people face such a problem as the inability to sink to the bottom. They just float to the surface. Others cannot open their eyes underwater. Still others, in general, hold their breath for only 10 seconds, after which the smell of their oxygen comes to an end. How to overcome all these difficulties and learn to swim underwater?

How to feel the water

In order to learn to swim underwater, you need to be able to feel the water. These simple exercises will help you feel more confident in the water. It is best to perform them in a pool or in shallow water. In any situation, you should feel the bottom. You can not train in a river with a strong current - it can be dangerous.

1. The first exercise is aimed at making you feel how the water pushes the human body to the surface. To do this, go waist-deep into the water, draw more air into your chest and sit down, clasping your knees. After a moment, your body will begin to rise and soon your shoulders will be on the surface. If you feel like you're out of breath, just get back on your feet.
2. The next exercise is aimed at getting rid of the fear of water contact with the face. Just lie face down on the surface of the water. If you are afraid that water can get into your ears, use special silicone earplugs for swimming. A special clothespin can be attached to the nose, although with a fixed air retention, water cannot enter the nose. When performing the exercise, you should lie on the surface of the water, like a jellyfish.
3. The next exercise is called "asterisk". It is similar to the previous one, but you need to lie not down, but face up. You should feel the water, how well it keeps a person on the surface. In this position, you can even breathe calmly.
4. The next exercise is most convenient to do in the pool. You just need to start pushing off the side with your feet and move. This will teach you to change your position in the water.

These exercises are designed to make you feel more confident. Most athletes who dive to a depth of tens of meters say that you need to fight fear in shallow water. Gradual immersion will make you feel like a fish in water, literally.

How to learn to dive

Most of those who dream of learning to swim underwater do not take into account the fact that they first need to learn how to dive. After all, if you just lie down on the surface of the water, you will not be able to dive to the depths. So how do you learn to dive?

The best way to learn to dive is in the pool. You need to start from the side of the pool itself, and then, if you wish, move on to towers of different heights. Stand right next to the side, bend over. Hands should be lowered along the legs. Then point your hands into the water and kind of push your body to jump. You must enter the water with your hands forward. Don't forget to take a deep breath before doing this. To go as deep as possible, you need to push off with your feet.

Diving in a natural reservoir is not very convenient, because there is no ledge. We'll have to jump from a place and learn to dive in shallow water. You can not dive in little-known places, especially from a cliff, a stone ledge, a steep bank. There may be hidden rocks at the bottom that you can hit your head against. In such cases, you can lose consciousness and choke - this is very dangerous.

Diving into the water is not difficult, the main thing is to overcome fear. Several intense workouts, after which diving will be easy and even fun. However, this alone is not enough to be able to swim underwater.

Breath holding is one of the main conditions of scuba diving. The amount of time you can stay underwater without breathing depends on how much oxygen your body can store. And the supply of oxygen, in turn, depends on the volume of the lungs and the rate of consumption of this oxygen. Lung capacity can be increased through constant training - this has been proven. Draw as much air into the chest as possible, trying to increase this volume each time. You can train with a hot air balloon. Fill it up in a few breaths, and then inhale as much air as you can from the balloon into your lungs. So you can clearly see the amount of oxygen inhaled.

It is very important to reduce vigorous activity underwater, which requires a lot of oxygen. You need to move very smoothly, all movements should be relaxed and soft. Professional swimmers say that during scuba diving they try to think less, get nervous, worry less. Because active brain activity also requires a lot of oxygen.

So, you learned to dive, hold your breath too. How to learn to swim in order to feel like a part of the water world?

First, get ready to dive in the water. After the dive has passed, try to swim not up, as usual, but to the side, along the bottom. To do this, you need to move your arms like a frog. Rake the water in front of you with your hands to move forward. The legs will help speed up the movement - they need to be moved gently, like fins. If the water pushes your body out, you need to work with your hands to deepen, that is, strive to swim to the bottom.

Separately, I would like to say about the eyes open under water. During the dive, try to open your eyes - it does not hurt at all. Sea water can cause a little discomfort, although many people hardly feel it. If you can’t overcome yourself and force your eyes to open underwater, use a mask or diving goggles. They should first be adjusted on the shore so that the rubber part fits snugly against the face.

Scuba diving

Diving is underwater swimming, which uses special equipment that allows you to stay at a depth for a long time. The most important thing in equipment is a cylinder with a gas mixture, which is used by a diver for breathing. With this tank, divers can stay under water for several hours. Also important is the wetsuit, which protects a person from the low temperatures that await him at great depths.

Diving can be simple, for fun - to enjoy the unusualness, beauty and originality of the underwater world. But often this is not only a hobby, but also a profession. Exploration work on the seabed is a highly demanded service. In addition, there is also sports diving, when athletes set various records.

Scuba diving is an interesting and exciting world that can surprise many ordinary people. After all, seeing with your own eyes pink reefs and a shell with a pearl is priceless. Learn something new, comprehend the unknown, strive to the bottom of the ocean to get to know our world from an unknown side.

Video: how to learn to feel the water

And here is the answer without any justification, just personal experience: I always dive when I swim, and I always open my eyes to see where I am swimming. In the pool, this is quite painful: the cornea becomes cloudy and reddens. In salt water, as a rule, it hurts from salt, although if the sea is not very salty, then it is normal (in Black, for example). Most of all I swim in fresh water - I live on the Volga. Every summer many, many times I dive into the Volga and open my eyes. They tingle already on the contrary from the fact that the eye is saltier than water, but in my opinion this is the least discomfort. And in all these years, nothing bad has happened to my eyes.

In my opinion, this is very unpleasant in any water - open eyes, like dry, rough underwear, uncomfortable, besides, you can’t really see anything, where is the top and the concrete block on the ascent path (they won’t hit along the way ...)? then it’s probably worth it, but something is already dumb for me from thinking about such underwater unpreparedness, I need a minimum of comfort - glasses for my eyes, and a bag of buffer air to my mouth - for a breather ... even breathing in a 2l bag for a minute or two is noticeably easier psychologically than hold your breath for the same time (relying on self-control, not omnipotent in this mechanism ...). Carbon dioxide, accumulating in the lungs, persistently and irritably makes the respiratory center "report on the current inhalation-exhalation", if you do not have time to ascend until you have the strength not to breathe, it will be inhaled by itself - reflexively like a sneeze ... barely taking a sip of water, the brain goes into StandBy Resource saving mode, turning off yourself and your (most significant) "salary", in favor of other organs that continue to work, the brain turns off (like a coma), the swimmer turns unconscious, breathing is stopped so as not to aggravate the trouble - saving glucose and oxygen at the same time big enough for the heart at least. After a few more minutes, the brain makes an attempt to “start up”, in case it was washed ashore by a wave, and after coughing in the air, you can come to your senses.

during ventilation (inhalation-exhalation) of the lungs, even 50% vol. carbon dioxide (and it’s unlikely to inhale) saturated in a bag (gas tank), although breathing is uncomfortable (it seems that you don’t actually breathe, but it’s still easier than not breathing anything), discomfort at the level of “it’s about to vomit”, where rapid breathing is practiced air - like chewing gum, distracting from the inevitably growing nausea, in fact, the danger of taking a sip of water at the same time is less than chopped off, and usually everyone chokes much earlier than they could be conscious when floating up ...

(Sold for 100 rubles in the FP store :) A 10-liter polyethylene corrugated (folding like a round accordion of clowns) bucket will be just super, especially if you fill it with oxygen, and not air, before diving,

at a depth of 10 meters, the pressure will reach 1 + 1 atmospheres (+ 1 atm \u003d 2 atm, that is, the pressure will double), 10 liters of gas in the buffer (corrugated bucket of 10 liters is this) will shrink to 5 liters, at 20 meters under water the pressure is 1 + 2 atm \u003d 3 atm, water compresses the chest and a bucket, a bucket shrinks up to 3.3 liters of a gas mixture, and it will be easy to breathe like on land, while the air hose descending from land down, with land air, pressure 1 atm, it will not be possible to inhale with a chest on which + 2 atmospheres 2 * 10-meter depth of the water column, as if there is a “twice vacuum” in the hose - you can’t suck anything in your mouth without a pressure recuperator machine, which even the special services don’t have yet.

why do we take "oxygen compressed 200 times" in the form of 50% hydrogen peroxide (it costs 150 rubles per liter in a chemical store, be careful!, it leaves unpleasant burns on the skin (if there was nothing to wash off immediately) unpleasant burns that feel like " dry ice", they pinch for half a day then "nibbling" white spots on their hands ..., it seems not deep and not fatal, but you need to take care of your eyes)

it is necessary to pour 10 ml into the "package" (buffer corrugated bucket) (generally 50 ml per 10 l of oxygen emission, but it’s impossible at once - it will tear the bucket with water vapor, I poured it in portions through the tap adding) hydrogen peroxide conc. a teaspoon of baking soda, and a pinch of potassium permanganate, you can put it inside wrapped in a film (then shake it to unfold) or inside a small vial or capsule. , which (starter potassium permanganate) is better to add through a tap (there is on the lid) into an already closed with a twisted lid, equipped with peroxide and soda (soda removes and turns off vinegar from peroxide - an inhibitor additive, which stabilizes peroxide preventing decay, without soda slower for an hour- two hisses the mixture releasing all the oxygen ...) "corrugated-bucket" (for example, starting potassium permanganate (you can drop a pharmacy iodine tincture into a tap) add inside a bucket that has been squeezed for now - through the tap available on its lid, dropping iodine or water solution into it potassium permanganate (any quantity is enough), and opening it for a moment (a pinch or drops of a solution of potassium permanganate or iodine tincture (iodine-crystal will not work, it is important in the tincture ... - there is potassium iodide) - the splashes fall into the corrugated bucket into the moment of opening the "samovar" cone tap, and then the bucket inflates, in a second, it becomes hot - like boiling water - you must let it cool before inhaling

Maybe once upon a time we were inhabitants of aquatic environments, we came out of the water. There is no point in arguing. The main thing is that now a person exists on land, there is not liquid around, but air, and our vision is adapted to work in air conditions, and not in liquid ones. But interest in water, with all its peculiarities and unusual features, remains. After all, we are constantly confronted with this substance, it plays an invaluable role in our life.

This article will help those interested in understanding underwater vision. It is clear to everyone since childhood that it is somehow not like that. But why? Some know the answer for sure, others do not even think about it, others intuitively guess, but cannot describe it in words.

Here you will find answers to questions that interest you, understand why water distorts the image of objects, why we see some strange picture in a liquid.

You will also learn how fish see and whether all fish see the same way, what is the main difference between the structure of the organs of vision of fish and humans.

In addition, the author's lengthy discussions on how our eyes would have evolved if we dived to live under the water surface await you.

Why do we see everything differently under water than in the air?

Let's start by answering this fundamental question. It would seem that water is a transparent substance, like air. And it should not interfere with getting a good picture. In fact, as most of us know, it interferes, makes the image unusual, fuzzy, not what we would like. Why? Let's try to figure it out quickly and simply.

Let us first recall what refraction is. This is when the waves of light, falling from one medium to another (in our case, from air to water) change their direction. It is because of refraction that the picture under water differs significantly from the picture on land.

The fact is that the refractive index of water (the ratio of the speed of light in vacuum to the speed of light in a given medium) is 1.34, the vitreous body, cornea (elements of the human visual organs) have the same indicator - 1.34, biological lens in our eye, - 1.43.

As you can see, there is either no difference between the indicators, or it is minimal. If they were completely identical, then, probably, we would not be able to see anything under water at all.

But there are still minimal differences. It is they that influence the fact that the image is focused not on the retina, as happens in people with good vision in the usual conditions for a person, but behind the retina, as in far-sighted people.

On the retina itself, the picture is muddy, fuzzy. Water is like a diverging biconvex lens.

It is interesting that persons with myopia, this is when the image is formed not on the retina, but in front of it, they see in the aquatic environment somewhat better than persons with good vision. In this case, it turns out that moisture with its refractive powers, as it were, corrects myopia, allowing the image to focus not in front, but on the retina itself.

And what about the fish?

Here are fish, they spend their whole lives under water. Moisture for them is a familiar environment where they hunt, breed, spend their free time, if they have it. We can say with confidence that they see what they need in the liquid. Surely nature took care of it. But why? What's in their eyes?

We answer. The fact is that in fish, the lens has a very convex shape, resembling a ball. Its refractive index is the largest when compared with the lenses of humans and all known animals.

It turns out that the difference between the refractive indices of moisture and the lens increases (the lens has more), as a result of which the image in fish focuses on the retina, they get a fairly clear, high-quality picture.

It should be emphasized that different fish have different visual abilities. For example, diurnal predators are the most vigilant. This is asp, pike, trout. They are able to detect food mainly through their eyes. Fish that eat plankton and benthic organisms see quite well.

But, for example, such freshwater inhabitants as burbot, pike perch, catfish, bream most often go hunting at night. Nature endowed them with a special structure of the organs of vision, which allows them to search for their victims at dusk.

In the eyes of night hunters there is a so-called tapetum. This is a special layer of guanine crystals, whose task is to concentrate the light that has passed through the retina and send it back to the retina.

It turns out that the same beam of light is used twice.

The tapetum is not only about fish hunting in the dark. This element of the organ of vision is present in terrestrial nocturnal predators.

And that is not all. Fish can see objects in the water at long distances. This happens due to a special muscle (falciform process), which is able to delay the lens.

But in general, fish are short-sighted. Most often, they are able to see the picture well at a distance of 1 - 1.5 meters.

The sharpest vision of underwater predators. If the water is clear and calm, they see objects at a distance of 10 - 12 meters.

We are sure you will be interested to know that some fish are able to illuminate the space around them themselves. It's all about the light energy that they produce. Thanks to this, we can observe an amazing phenomenon - luminous creatures swim in the darkness of the underwater depths.

It should be noted that fish, like animals, are very, very different. Each species has its own living conditions, its own food, its own interests and habitat. Accordingly, fish also have some differences in the structure of the organs of vision, which allows them to live in such conditions.

In general, the role of vision as a source of information in aquatic life is very significant. This is not only the search for and capture of food, but also orientation in space, and the preservation of the flock, and reproduction ...

Factors affecting the quality of human vision underwater

With refraction, everything is clear. This is the main reason why we can't see well underwater. But she's not the only one. Even if we assume that the refractive index of moisture is different, we still would not get the same picture as in air.

Why? Let's think together.

First. Water is not the natural habitat of the human eye.

Remember, for example, how you dive in a river and open your eyes. You don't feel very comfortable, do you?

Of course, you can get used to everything. But the fact that lovers with open eyes to swim under water most often emerge with reddened eyes is a fact. Human eyes lack some kind of protective mechanism that would save the mirrors of the soul from discomfort.

Second. Water composition.

Even ideal life-giving moisture would not be suitable as a comfortable environment for our organs of vision. But nothing is perfect!

We are faced, for example, with river water. First of all, it is not very transparent. And that's putting it mildly. Secondly, it is full of impurities that can additionally irritate the mucous membrane of the eyes. The result is an even fuzzier, blurry picture.

Or here is the life-giving moisture of the sea. Some argue that it is somewhat more comfortable for human eyes than fresh liquid, because it contains a certain amount of salts, and their concentration is similar to the concentration of salts in our bodies. This is partly true.

The fact is that in different reservoirs the concentration is different. Here, for example, most of the salts in the Red and Dead Seas. And least of all about the inland seas, such as the Baltic and Black.

It turns out that the closer the level of salt concentration in water to the same indicator in humans, the more comfortable we will feel when opening our eyes under water. The Black and Baltic Seas win here. You can safely swim and dive in them without fear of irritation of the mucous membranes.

Things are quite different in more saline water bodies. There, a person runs the risk of getting quite a serious irritation of the mucous membranes. Even the skin, if it is too delicate, can suffer from the effects of salts.

In any case, open-eyed swimming in marine conditions should be treated with caution. It is recommended to get used to it gradually.

By the way, there are also safe-looking reservoirs, swimming in which with open, unprotected eyes is not desirable. These are therapeutic mineral pools with a high content of hydrogen sulfide. This component irritates the mucous membranes, as evidenced by a fairly strong pain.

But we went very far, to rivers and other bodies of water. Meanwhile, you can immerse yourself in life-giving moisture and open your eyes in it right at home, in the bathroom. This is what most children do during their proper bathing, which we do not doubt.

Here, completely different impurities can negatively affect the organs of vision, and the main one is chlorine. It is this substance, which is, in fact, a poison, which negatively affects the mucous membrane, causing quite serious redness and irritation. It is clear that in this state, the eyes are unlikely to be able to get a good picture while under water.

How can you improve your vision underwater?

So, we have already discussed why the image is fuzzy under water, and also what can make it even worse. Now we need to focus on the following: how can we improve the quality of the resulting image? How, immersed, to see the maximum of everything?

The answer to this question is quite simple. Need some kind of transparent partition between the eyes and the liquid. And such a partition becomes underwater glasses and underwater masks. In them, people actively swim, navigate in space, see far enough and with high quality. Now it remains only to find out why this happens.

Remember, we wrote about the fact that water does not have the same refractive index as air. And so the picture when diving is bad. Everything changes when a layer of air appears between the water and the eye, i.e. familiar environment. Underwater masks and goggles provide just that, which allows you to make the underwater world clear and attractive for a person.

Of course, additional devices will not solve the problem of turbidity of life-giving moisture, which can significantly limit the view. It is clear that snorkeling in the river and in the sea are two different things. But still…

Miracles of refraction

In an article about vision under water, we cannot fail to mention the miracles of refraction, about how objects that are in water change.

It turns out that most children at a certain period of their lives are puzzled by the question (approximately): why do the sizes of the same ball on land and in a container of water differ? Similar questions are about why a body immersed in a typed bath becomes large. Or why a pencil that is not completely immersed in a glass of water seems broken.

All this is the miracles of refraction, which are not miracles at all, but the result of physical laws. Here, for example, the increase in objects.

Yes, indeed, it is. If we take, for example, a children's cube and, having previously measured it with a ruler, lower it into a glass vase with thin walls, we will observe the following. When measured, the side of the cube will become larger by about 33% (plus the walls of the vessel will play their small magnifying role).

It is clear that the point is not that the cube was saturated with moisture and swollen. It's all about the refraction of light. Because of him, our legs look strange when we lie in the bathroom. Because of it, objects under water seem closer than they actually are, by about 25%.

In general, moisture, as we already wrote, is a kind of lens, so the image is obtained approximately as after a biconvex lens.

What if…

Many are interested in how the organs of vision of a person would change, how they would evolve if he was forced to live in the water depths. Let's try to think about the answer to this question together.

Firstly, the way of life that a person would lead is important.

If he swam closer to the surface, it's one thing, but at a depth where there is much less light - another. Therefore, probably, a tapetum would appear in the structure of the organ of vision, i.e. a layer of crystals that collect light.

Secondly, the human eye is now quite sensitive in water, the liquid can cause irritation and redness.

Therefore, if you change the habitat to water, you need to acquire special protective films that would limit the effect of moisture on the elements of the organs of vision.

Thirdly, the question of the refraction of light.

Let the liquid - not the environment where, in principle, you can see as well as on land. But some fish see at 10 - 12 meters. And all, including, thanks to the lens of a convex shape. It would not hurt the same person, so that the picture is focused not behind the retina, but on it, and was clear and of high quality.

Fourth, coverage of the territory.

It also wouldn't hurt to increase it. Yes, a person's head is actively moving, but will this be enough in the underwater world? Is not a fact. Therefore, it is quite likely that the organs of vision will increase somewhat and leave the orbits somewhat, will rotate more actively and will be able to capture more information. It is also possible that the location of the eyes will change - they will move apart somewhat.

So far, life-giving moisture for a person is only a temporary environment in which he feels relatively comfortable. Long and long years of evolution are needed for us, our organs of vision, to be able to live in the water as comfortably as on land.