SCUBA Diving

• What is SCUBA diving?
• When was SCUBA diving invented?
• What equipment do scuba divers usually use?
• How does the scuba diving equipment adapt us to swim like a fish?
• What is the difference between SCUBA diving and snorkeling?
• Why do my ears hurt when I dive underwater?
• What other ways is my body affected when I scuba dive
• What are "the bends’?
• What is a diving computer?

What is SCUBA diving?
The letters in the word SCUBA stand for Self-Contained Underwater Breathing Apparatus. Scuba refers to diving underwater breathing from an air tank and regulator assembly. Scuba divers carry their air with them on their back in an air tank. A scuba diver is able breathe underwater from the air tank using a regulator that controls (regulates) the flow of air from the air tank into the diver’s mouth.

• When was SCUBA diving invented?
SCUBA diving was invented in 1943 when the Frenchmen, Jacques Cousteau and Emile Gagnan developed the first scuba diving regulator. Before that time divers had to be connected to the surface with an air hose. Air was pumped down from the surface to the diver through the air hose. With the invention of SCUBA diving divers no longer had to be attached to the surface.

Captain Jacques Cousteau, co-inventor of SCUBA diving equipment.

What equipment do SCUBA divers usually use?
During our expedition the equipment we will be using is typical of what most scuba divers use.


This covers our eyes and lets us see clearly underwater. It also covers our nose and keeps water from going up our nose. (We hate water up our nose!)

A special tube we breathe through while swimming on the surface so we don't have to waste the air in our air tank.

FINS - These paddle-like shoes give us more power for swimming underwater.

A rubber suit is worn to help keep us warm underwater and to protect us from getting cut or scratched. In Caribbean Sea we wear a very thin, one-piece, wet suit because the water here is so warm.

AIR TANK - A metal container that safely holds that air we breathe underwater. When empty our air tank is refilled with a special air pump, called an air compressor.

This gives us air from our air tank. We connect the regulator to the air tank and breathe from the regulator mouthpiece. The regulator has extra outlets that we use to connect our BC air hose and the air pressure transmitter for our dive computer.

BUOYANCY COMPENSATOR (BC) - An inflatable vest we wear that allows us to control our buoyancy (floating and sinding) underwater. (A BC allows us to become neutrally buoyant underwater.) The BC is attached to our air tank and works like a backpack so we can carry our air tank on our backs. The BC has pockets so we can carry things and rings that we use to hook things, like our dive light, so we don't have to hold it in our hands. Our new BCs also have abuilt-in weight belt, so we don't have to wear a separate belt with weights on it.

DIVING COMPUTER - This is a special water-proof computer that we wear on our wrist. It tells us everything we need to dive safely. It shows us how much air is in our air tank, how deep we are, how long we have been underwater, when we must go back up to the surface, and how long we can stay underwater if we make another dive.

We wear this on our wrists to help us find our way underwater.

DIVE KNIFE - This is not a weapon. This is a tool we use underwater for cutting, prying, digging, pounding, measuring.

This is a water-proof light we use day both day and night. During the day we use are light for looking under corals, in caves or exploring shipwrecks. At night we use our light to see where we are going.

To learn more about Aqua Lung SCUBA diving equipment - click here.

• How does the SCUBA diving equipment adapt us to swim like a fish?

GILLS – Fish can take oxygen from water like our lungs can take oxygen from air. Our lungs can’t take oxygen from water like a fish’s gills so we carry our air with us in our air tanks and put our regulator in our mouth so we can breathe underwater.

FINS – We don’t have fins to push us easily through the water like a fish, so we wear large scuba diving fins to swim underwater like a fish.

SWIM BLADDER - Most fishes control floating and sinking with a little balloon inside their bodies called a swim bladder. The fishes can put air inside their swim bladders, which will make themselves float (positive buoyancy). The fishes can squeeze the air out of the swim bladders, which will make themselves sink (negative buoyancy). The fish easily float underwater (neutral buoyancy) by controlling the amount of air inside their swim bladder. We don’t have a swim bladder and our lungs don’t work like a swim bladder so we have to wear a buoyancy compensator (BC). By adding or releasing air from our BC we can control floating and sinking the same way a fish uses its swim bladder to float or sink.

EYES – Fish have eyes designed to see clearly underwater. Our eyes can’t focus underwater, so everything looks blurry. We must put on face mask to see clearly underwater like a fish.

What is the difference between SCUBA diving and snorkeling?
When we SCUBA dive we breathe air from an air tank. When we snorkel we breathe air from a snorkel. Whether we are snorkeling or scuba diving we wear some of the same equipment: mask, snorkel, fins, and wet suit. When we are SCUBA diving we can stay underwater as long as the air lasts in our air tank. When we are snorkeling we can stay underwater only as long as we can hold our breath.

When we are exploring shallow coral reefs it is usually easier to snorkel and make shallow dives holding our breath. When we are exploring deeper reefs or shipwrecks it is easier to SCUBA dive because we can dive deep and stay underwater longer.

AQUA LUNG/ U.S. DIVERS CO. Snorkeling Equipment




To learn more about Aqua Lung snorkeling equipment - click here.

• Why do my ears hurt when I dive underwater?
Have you ever dove down to the bottom of a swimming pool and felt your ears hurt? That is because of the pressure that increases on your body as you dive deeper underwater. Have you wondered why divers aren’t squished flat like a bug when they dive deep underwater? That is because our bodies are mostly water and water can’t be compressed, or squeezed, like air. When we dive we usually only feel the increase in pressure in our ears, just like you felt when you dove to the bottom of the pool. To prevent our ears from hurting we simply pink our nose and try to blow into our nose. Blowing into our nose with our nose pinched forced air into our middle ear and equalizes the pressure in our ears. The key to scuba diving is equalization. When the air pressure inside our bodies is equal to the pressure pushing on us, we don’t feel any squeeze. Our scuba diving regulator automatically regulates the air pressure inside our bodies as we breathe so the pressure inside our bodies is the same as the pressure pushing on our bodies from the water.

• What are other ways my body is affected when I scuba dive?
Magnification - Water makes everything you see look bigger than it really is. Water magnifies everything to look 25% larger and 25% closer to you than it really is. That fish you saw that was 4 feet long was really only 3 feet long!
2) Color Loss – The light we see from the sun is actually made off all different colors mixed together. Do you know the color spectrum Roy G. Biv? The water absorbs the colors as you dive deeper underwater. First red disappears, then orange, then yellow, until below 60 feet underwater all we see are green, blue, gray, or black. If you are diving deep and you scratch your hand on a sharp piece of coral you’ll be grossed out! It doesn’t look like a little red blood…It looks like green goo coming out of your hand!
3) Light Loss – As each color from the light is absorbed there is less and less light as you dive deeper and everything is dimmer.

Further Hearing - Sound travels further underwater than in air. When you are scuba diving you are not in a silent world. You will hear many strange and interesting sounds from grunting fish, snapping shrimp, squeaking dolphins, and even far away boat engines.
2) Faster Hearing – Sound travels about four times faster underwater than in air. The increased speed of sound confuses your brain when it tries to tell you where the sound came from. Underwater, the sounds seem to be coming from all directions at once.

It is almost impossible to talk underwater. Your vocal cords don’t work in water and you have a regulator mouthpiece stuck in your mouth. Underwater we communicate using hand signals.

Water is about 800 times denser than air. Ever tried to run in a swimming pool? It’s like running in slow motion. Because the water is so thick we can only move slowly. To move easily and save energy we try to swim horizontally with our arms next to our sides and kick slowly with our legs. If you try to move too fast you can quickly get tried out underwater.

Ever wanted to be Superman? You can be underwater. Every try to pick up your friend in a swimming pool? They are a lot lighter in the water than out of the water. Objects that are not very dense or have air inside are a lot lighter in the water. Underwater you can often easily pick up things that you could barely lift on land.

Water absorbs heat about 20 times faster than air does. Your body will get chilled faster in water than in air. Even 80ºF water can feel chilly after a while.

• What is "the bends"?
Also called decompression sickness, "the bends" is something that can happen to our bodies, when we’re scuba diving, because of pressure. Take a soda bottle and look inside. Do you see any bubbles inside? Now, shake the bottle and open it. What happens? Of course the bubbles makes the soda squirt out! That is what can happen in your body if you get the "bends". Now your blood is not going to squirt out of your body, but you can get tiny bubbles in your blood and these bubbles can be dangerous to your nervous system. As we go deeper and deeper underwater more and more gas (nitrogen) gets dissolved into our blood. If we stay down to deep and come up to fast those tiny bubbles can form in our blood and body tissues. To prevent getting decompression sickness we use diving computers.

• What is a diving computer?
We can’t play games or surf the net on our diving computer. We wear our diving computer on our wrist and use it for diving safely and to avoid getting "the bends". Our diving computer keeps track of how deep we are and how long we have been at different depths, and it calculates how much time we can safely spend underwater without getting the bends. The diving computer has a graphic and digital readout that we check often during our dive. We always try to come back to the surface before we run out of time. If we stay underwater too long, our diving computer tells us to make a brief stop on our way back up to the surface. This stop is called a decompression stop. A decompression stop allows the excess nitrogen gas to escape safely from our bodies with becoming "the bends". Our diving computer tells us at what depth and for how long to make a decompression stop. To dive safely scuba divers avoid staying underwater too long so they won’t have to make decompression stops.

On our expedition we are using special diving computers that also tell us how much air is in our air tanks and how much time we have left before we get low on air.

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