How Deep Can You Scuba Dive? Exploring How Our Bodies Adapt

Q: What Happens to Your Body When You Scuba Dive?

Immersion As you dive, the pressure pushes blood from your legs to your chest. This makes your heart work harder and can raise your blood pressure. You might notice a heaviness in your chest the deeper you go. Pressure Have you ever swum to the bottom of a deep pool and felt discomfort in your ears? Now, imagine diving eight times deeper. The deeper you dive, the greater the pressure on your body. This increased pressure affects your sinuses, ears and lungs, which may cause pain and an inability to breathe deeply. Blood flow to your brain also increases, which can intensify sensations of tightness or pressure throughout your body. Cold The deeper you go, the colder the water becomes. As you descend into the cooler water, your blood vessels constrict, causing your heart to work harder to pump blood through them. This increase in pressure can make your body feel cold and stiff.

Q: What Are the Risks of Scuba Diving?

Decompression sickness This occurs when divers ascend too quickly, causing nitrogen bubbles to form in their tissues. Symptoms may include dizziness, joint pain and paralysis — and in severe cases, it can be fatal. The condition earned the nickname “the bends” because the intense bone and joint pain can cause affected divers to double over in excruciating pain. Barotrauma This injury happens when pressure differences between the inside of the body and the surrounding water cause damage. For example, sinus barotrauma occurs when unequal pressure affects the sinuses, leading to pain, nosebleeds or even facial swelling. Other forms of barotrauma may affect the lungs or ears. Arterial air embolism This serious condition results from pulmonary barotrauma: when expanding air becomes trapped in the lungs during ascent. If air bubbles enter the arterial bloodstream, they can block blood flow to vital organs, potentially causing a stroke or heart attack. Divers can reduce the risk by breathing continuously and ascending slowly to avoid lung over-expansion. Nitrogen Narcosis Divers who descend below 100 feet are at risk of nitrogen narcosis, where excess nitrogen under pressure affects the nervous system. This can impair judgment, coordination and decision-making, sometimes giving divers a sensation similar to intoxication.

When you think of scuba diving, one of two things probably comes to mind: the thrill of checking off a bucket list adventure, or the cautionary tales about divers surfacing too fast and getting “the bends.”

Either way, there are likely plenty of questions swimming around your head. How deep can you actually dive? How does your body adjust to being underwater? And what are the real risks you should know about?

We’re here to dive into the answers to all your burning scuba diving FAQs.

How Deep Can a Scuba Diver Go?

Just how far you can venture into the ocean’s depths (or that cenote, quarry or lake you’ve been eyeing) depends on a few key factors, like your diving experience and the environment itself. For most recreational scuba divers, the safe limit is around 130 feet (or 40 meters).

However, some divers go well beyond that. Welcome to the world of technical diving: a more advanced form of scuba that takes you deeper into caves, shipwrecks and other underwater landscapes. Technical divers rely on specialized gas mixtures with specific concentrations of oxygen, nitrogen and helium, carefully calibrated to match the dive’s depth and duration. With this specialized gear and training, they can safely reach depths of up to 330 feet (or 100 meters).

What Happens to Your Body When You Scuba Dive?

With the right equipment, you can dive deep enough to explore endless underwater oases and shipwrecks. But what exactly happens inside your body as you go deeper and return to the surface? Let’s break it down:

Immersion
As you dive, the pressure pushes blood from your legs to your chest. This makes your heart work harder and can raise your blood pressure. You might notice a heaviness in your chest the deeper you go.

Pressure
Have you ever swum to the bottom of a deep pool and felt discomfort in your ears? Now, imagine diving eight times deeper.

The deeper you dive, the greater the pressure on your body. This increased pressure affects your sinuses, ears and lungs, which may cause pain and an inability to breathe deeply. Blood flow to your brain also increases, which can intensify sensations of tightness or pressure throughout your body.

Cold
The deeper you go, the colder the water becomes. As you descend into the cooler water, your blood vessels constrict, causing your heart to work harder to pump blood through them. This increase in pressure can make your body feel cold and stiff.

How Does the Human Body Adapt to Diving?

They rely on the mammalian dive reflex, a natural response seen in all mammals when submerged in water. This reflex kicks in immediately when divers go underwater and hold their breath. It helps conserve oxygen by slowing the heart rate and constricting blood vessels.

The body responds with bradycardia (slower heart rate), apnea (a temporary pause in breathing) and increased blood vessel resistance. This effectively slows the heart’s beats per minute and redirects blood to vital organs, conserving oxygen for essential muscles.

But it’s not all automatic: Divers also train their bodies to adapt to deeper dives and the increased pressure on their lungs. Through specific breathing exercises and lung training techniques, they can improve their oxygen efficiency and increase lung capacity, allowing them to dive deeper and stay submerged for longer.

What Are the Risks of Scuba Diving?

As with any adventure sport, there are risks involved when scuba diving. As mentioned earlier, divers can get decompression sickness (the bends) or other conditions related to increased pressure and gas absorption.

Below, we explain some of the risks of scuba diving:

Decompression sickness
This occurs when divers ascend too quickly, causing nitrogen bubbles to form in their tissues. Symptoms may include dizziness, joint pain and paralysis — and in severe cases, it can be fatal. The condition earned the nickname “the bends” because the intense bone and joint pain can cause affected divers to double over in excruciating pain.

Barotrauma
This injury happens when pressure differences between the inside of the body and the surrounding water cause damage. For example, sinus barotrauma occurs when unequal pressure affects the sinuses, leading to pain, nosebleeds or even facial swelling. Other forms of barotrauma may affect the lungs or ears.

Arterial air embolism
This serious condition results from pulmonary barotrauma: when expanding air becomes trapped in the lungs during ascent. If air bubbles enter the arterial bloodstream, they can block blood flow to vital organs, potentially causing a stroke or heart attack. Divers can reduce the risk by breathing continuously and ascending slowly to avoid lung over-expansion.

Nitrogen Narcosis
Divers who descend below 100 feet are at risk of nitrogen narcosis, where excess nitrogen under pressure affects the nervous system. This can impair judgment, coordination and decision-making, sometimes giving divers a sensation similar to intoxication.

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Sources:
https://oceanexplorer.noaa.gov/technology/technical/technical.html
https://dan.org/health-medicine/health-resource/dive-medical-reference-books/the-heart-diving/basics-of-your-heart-circulatory-system/#affects
https://pubmed.ncbi.nlm.nih.gov/30855833/
https://pmc.ncbi.nlm.nih.gov/articles/PMC11168797
https://pmc.ncbi.nlm.nih.gov/articles/PMC7965165
https://www.ncbi.nlm.nih.gov/books/NBK470304