What’s better than cracking open a cold beer after a solid day of diving? It’s a bit of a tradition in many places, and let’s be honest, it feels well-earned. But how safe is that deco beer we all love to toast with? And more importantly, how does alcohol actually affect our bodies before and after diving?
In this blog, we’ll look at the risks that come with mixing alcohol and diving, why it’s more dangerous than it might seem, and when it’s actually safe to raise that glass.
Let’s start with how alcohol affects the body in general
Alcohol is a central nervous system depressant, it slows everything down. Not just in terms of mood, but your brain’s communication pathways, reaction time, coordination, balance, memory, and decision-making. That doesn’t sound like something you want to mess with while planning, executing, or recovering from a dive.
Physiologically, alcohol consumption causes:
• Increased heart rate and blood pressure
• Dilated blood vessels
• Impaired thermoregulation (you feel warmer but lose heat faster)
• Dehydration due to its diuretic effect, it blocks the release of an anti-diuretic hormone, making you pee more
• Suppressed immune function
• Reduced liver function and ability to metabolise toxins
• Reduced REM sleep, so even if you sleep after drinking, you don’t rest properly
And over the long term, excessive alcohol intake increases the risk of cardiovascular disease, liver disease, some cancers, and hormonal imbalances.
How does alcohol progress in the body?
Here’s a rough breakdown of what different blood alcohol levels (BAC) do to your system:
• 0.01–0.05% BAC (1–2 drinks): You feel more relaxed and confident. Mild impairment of judgment and coordination begins.
• 0.06–0.10% (3–5 drinks): Clear impairment in reasoning, reaction time, depth perception, and peripheral vision.
• 0.11–0.20% (5–7+ drinks): Significant loss of motor control, balance, and memory. Emotions become exaggerated.
• 0.21–0.30% and above: Confusion, stupor, possible blackout. Risk of vomiting, unconsciousness, and respiratory depression.
What matters here is that even a couple of drinks can affect your body’s hydration, thermoregulation, and neurological function, all of which are important when diving.
Why is alcohol before diving such a terrible idea?
Alcohol can directly or indirectly increase the risk of:
1. Decompression Sickness (DCS)
DCS happens when nitrogen absorbed into the body under pressure forms bubbles in the blood and tissues during or after ascent. Alcohol increases this risk by:
Dehydrating you : reducing blood plasma volume and increasing bubble formation
Altering circulation : leading to uneven perfusion of tissues
Delaying symptom recognition : you might ignore or not notice the early signs
Delaying treatment : especially in remote dive locations where timely evacuation is important
2. Nitrogen Narcosis
Also known as the “rapture of the deep,” this can already cause poor decision-making, confusion, and euphoria. Add alcohol into the mix (or even just its lingering effects), and you’re compounding this impairment.
3. Hypothermia
Alcohol gives a false sense of warmth. It causes blood vessels to dilate, making your skin feel warm, but it actually speeds up heat loss; not ideal in colder dive conditions.
4. Dehydration
Dehydration reduces the volume of circulating fluids, increases blood viscosity, and slows down nitrogen elimination. A dehydrated diver is far more likely to get DCS than a well-hydrated one.
5. Delayed reaction and poor decision-making
Whether it’s monitoring your air, adjusting buoyancy, staying with your buddy, or managing an emergency, impaired judgment can be dangerous or even fatal underwater.
What about drinking after diving?
Good question (...) and where most divers actually mess up.
After a dive, your body is still off-gassing nitrogen. This process takes time, and your body needs to be in good shape to manage it. Having a beer or two immediately after surfacing might seem harmless, but:
• Alcohol still causes dehydration, which slows nitrogen elimination
• Alcohol impairs judgment, you may not notice or downplay early symptoms of DCS
• It might affect your sleep that night, which slows recovery if you’re diving again the next day
Some dive organisations recommend waiting at least 1 hour after diving before consuming alcohol. If you’ve done a deep or multiple dives, or you're planning to dive again soon, it's better to wait several hours, or just save the drinks for the evening.
How long should you wait to dive after drinking?
That depends on how much you’ve had.
The liver metabolises alcohol at a rate of about 1 unit per hour.
But other effects, like dehydration, fatigue, and cognitive impairment, may linger for 8 to 12 hours or more, depending on the person.
A general rule: Avoid diving within 12 hours of drinking, especially if you had more than 2 standard drinks. And definitely avoid diving with a hangover, the combination of dehydration, fatigue, and brain fog is risky at best.
Does this mean I can’t enjoy a drink on my dive trip?
Not at all! It just means you should be smart about it:
• Hydrate well before and after every dive
• Avoid alcohol the night before an early dive
• Wait at least an hour after your last dive before drinking , longer if you can!
• Limit alcohol if you’re diving again the next day
Listen to your body - if you’re tired, headachy, or foggy, don’t dive!
Diving demands clarity, focus, physical control, and teamwork, the exact things alcohol messes with. That post-dive beer? It hits best when it follows a solid, safe day of diving, not when it compromises your safety or your dive buddies’.
So keep the drinks on dry land, toast the day after the tanks are rinsed, and remember:
• Drinking and diving don’t mix ; You Booze, You Lose.
Cheers to safe diving and smart partying!
