When you go swimming, the water around you is pressing against you, creating pressure. As you go deeper into the water, more water is pressing against you. You can feel that pressure in your ears even at 10 feet. If you've dived to the bottom of a swimming pool, you've probably felt that pressure.
The normal pressure you feel at sea level is considered normal atmospheric pressure or 1 ATA (Atmospheres Absolute). As you go into the water and pressure changes your ATA changes as well. For every 33 feet you descend in the water, you gain one ATA. So at 33 feet you would have a total of two ATA's: one for the 33 feet of water and one for normal atmospheric pressure.
Sometimes your depth is referred to as ATMs (Atmospheres) which does not include your regular atmosphere, so at 33 feet deep you would have one ATM. It's not as official, but it can be good to know what people may be talking about.
Water pressure affects a lot aspects in breathing while swimming, whether going scuba diving, freediving, or snorkeling, so here are some facts.
If you are certified to scuba dive, you probably know there are different air tanks to use while diving at different depths. This is because gases compress differently under pressure. The normal air we breathe is roughly 20% oxygen and about 80% nitrogen. As you dive deeper in the water, however, oxygen doesn't condense the same as nitrogen, so air tanks must be filled with less oxygen for deeper dives.
Now as you get deeper, you also don't want to be taking in too much Nitrogen or you can experience Nitrogen Narcosis, which is very dangerous for divers, so there are air tanks called Trimix, which have helium in them as well to balance air intake at deeper levels.
FREEDIVING AND SNORKELING
Pressure affects you at every depth in the water, even when you're snorkeling at the surface. While you are snorkeling around, looking at coral or swimming with bio-fluorescent turtles, the water around you is pressing your lungs and your diaphragm has to work harder to help you breathe. That is why we have created a pressure-regulated snorkel which helps you breathe easier.
Freediving requires a few more precautions than snorkeling because as a freediver descends, their lungs will shrink in size and the oxygen inside their body compresses, which is fine. The problem is as they ascend, their lungs expand and the oxygen expands, which can cause a condition called "shallow water blackout." If not watched carefully, a freediver can black out upon ascent and drown.
These are a few helpful tips on water pressure. We hope it has helped you. Be sure to check out our pressure-regulated snorkels and pick your favorite color!