Alcohol and diving safety: how it increases dehydration risk and impairs judgment

What is the effect of alcohol on diving?

• A. Enhances diving performance
• B. Increases risk of dehydration and impairs judgment
• C. Provides a warming effect in cold water
• D. Improves coordination for diving tasks

Answer: (B)

Alcohol significantly increases the risk of dehydration and impairs judgment, making option B the most accurate response. When divers consume alcohol, it affects their body's ability to retain water, leading to dehydration, which can be particularly dangerous under water due to the physical demands of diving. Dehydration can increase the risk of decompression sickness and negatively impact overall physical performance. Furthermore, alcohol consumption impairs cognitive functions and judgment, which are critical for making sound decisions while diving. Good decision-making is essential to respond to any unexpected situations that may arise underwater, such as changing currents or potential hazards. An impaired state can lead to reckless behavior, delayed reactions, and poor assessment of risks, all of which elevate the chances of accidents. In contrast, the other options misleadingly suggest positive effects of alcohol that are not supported by diving safety practices or physiological realities.

Alcohol and the Open Water Adventure: Why It’s a Bad Combination

If you’re gearing up for an open water outing, the quick answer to “What happens when alcohol is involved?” is straightforward: it raises dehydration risk and it clouds judgment. That combination is a real threat when you’re in a dynamic, buoyant environment where timing, awareness, and smooth gas management matter. Let me break down why this matters, in plain language, and how it connects to what you learn in IANTD Open Water Diver training.

Dehydration first: what alcohol does to your body

Imagine your body as a careful engine that likes to keep fluids in balance. Alcohol throws a wrench into that balance. It’s a diuretic, which means it makes you produce more urine. The result? You can lose a surprising amount of water, and fast. Underwater, even small amounts of dehydration can become big problems because you’re working harder than you would on land—breathing, moving against currents, keeping your buoyancy stable, and staying warm in cooler water.

Dehydration isn’t just “feels dry” grumbling. It can reduce plasma volume, thicken the blood slightly, and make it easier for gas to form bubbles when you ascend. That last part matters because decompression stress is a key risk in many open water settings. If your body isn’t holding onto water the way it should, your gas exchange efficiency can slip, and you’ve got less margin to handle the ascent phases safely.

Then there’s the cognitive side. Alcohol doesn’t just dry you out; it muddles your thinking. Reaction times slow, judgment gets fuzzier, and situational awareness takes a hit. In an underwater context, that combination is dangerous. Imagine a sudden current shift, a snagged hose, or a sighted hazard—clear, fast decisions are your lifeline. When your brain isn’t firing on all cylinders, those moments don’t go as smoothly as you’d hoped.

Let’s connect the dots to the water you love

You’ve trained to buddy-check, to fine-tune buoyancy, and to monitor your gas mix and depth. Those skills rely on precise perception and sound judgment. Alcohol chips away at those pillars. It’s not just about avoiding a bad judgment call, though. Hydration affects your physical performance too—your endurance, your ability to maintain comfortable core warmth, and your overall stamina as you move through longer excursions. In cold, variable water, dehydration can sneak up on you where you least expect it.

Now, what about those other answer choices you might hear?

• A. Enhances diving performance: Not true. Alcohol doesn’t boost performance. It undermines hydration, judgment, and coordination—three things you need for a safe underwater outing.

• C. Provides a warming effect in cold water: That’s a misconception. Alcohol actually makes you feel warmer because it causes blood vessels to dilate near the skin, which can lead to a misperception of warmth. In reality, your core temperature can drop faster, and that’s risky when you’re in colder water or dealing with cooler air temperatures on land before and after immersion.

• D. Improves coordination for diving tasks: Nope. Coordination suffers under the influence, not improves. You want precise hand signals, steady trim, and controlled movements—things that don’t mix with alcohol.

A quick real-world aside: the human moment

Think about a typical SCUBA outing with a buddy. You plan a shallow, calm entry, check your equipment, do you pre-dive safety checks, and keep communication tight. Now picture someone who’s had a few drinks the night before or even earlier in the day. They might feel relaxed, but the reality is their hydration is off, their decision-making is slower, and their ability to respond to a sudden shift in current or a buoyancy hiccup is compromised. The buddy system is a safety net, but it’s only as good as the people using it. If one member isn’t thinking clearly, the whole group bears the risk.

What this means for your training and approach

In IANTD Open Water Diver training (the kind of learning you’ll engage with in real life, not just on a test), safety rests on a few keystones: hydration, pre-dive checks, buddy coordination, and careful gas management. Alcohol undermines every one of those. If you’ve had alcohol, your hydration status is likely off, your cognitive sharpness is reduced, and your physical performance—like maintaining neutral buoyancy or performing a controlled ascent—can suffer.

That’s why the message you’ll hear echoed in classrooms and on boats is simple and practical: avoid alcohol for a substantial period before a water outing. The common guidance you’ll encounter is to skip alcohol for at least 24 hours before diving. It’s not a hard medical rule, but it’s a pragmatic standard that helps keep the water experience safer, more predictable, and more enjoyable for everyone involved.

Practical steps you can take right now

If you’re serious about keeping your water time safe and fun, here are concrete moves that align with good training and common-sense safety:

• Hydrate well in the days leading up to an outing. Water and electrolyte drinks can help you maintain balance, especially if you’ve been active or the weather’s warm.

• Plan alcohol-free days around water time. If you’re going out in the morning, afternoon, or after a long surface interval, choose hydration-heavy, non-alcoholic beverages that won’t leave you light-headed or parched.

• Eat smart. A light meal before entering the water helps stabilize blood sugar and can support energy levels, which matters when you’re managing buoyancy and task loading.

• Use the buddy system as a reminder tool. Make a pact with your buddy to check for signs of dehydration and fatigue in each other. A quick “how’s your water intake today?” can be a simple safety net.

• Know your signs. Thirst, dark urine, dry mouth, headaches, dizziness, or fatigue aren’t just landlubber complaints—they’re your signals. If you notice them, postpone or cancel the water outing and rehydrate, rest, and reassess.

A few more perspectives you’ll appreciate

• Hydration isn’t a one-off thing. It’s part of a routine that starts well before you step onto the boat. Think of it like equipment maintenance: you don’t skip it because you’re in a hurry.

• Alcohol can affect perception of cold, wind, and water temperature. In some environments, that misperception can push you toward underestimating risks—like a rapidly cooling night surface interval or a chilly dawn dive where warmth and mobility matter.

• It’s okay to make a different choice. If you’ve already had a drink, you’re not “cancelled” from all water activities. You simply choose to reschedule, rehydrate, and rejoin when you’re in a safer physical and mental state.

Connecting back to the bigger picture

The open water world is full of small, powerful moments—the way sunlight filters through the surface, the way your buoyancy changes as you move, the calm hum of your regulator, the patience you show a new student or a hesitant buddy. Alcohol isn’t cruel on purpose; it just doesn’t belong in a space where timing, judgment, and coordination matter so much. That’s why safety guides emphasize hydration and clear-headed decision-making as non-negotiables.

If you’re exploring topics within your open water training, you’ll see this theme pop up again and again: the best learning happens when you show up with your body rested, hydrated, and focused. The water rewards that kind of preparation with smoother, safer adventures and a better overall experience for you and your teammates.

Bottom line

The effect of alcohol on a SCUBA outing isn’t a mystery. It’s simple and practical: more dehydration risk, and impaired judgment. That combination increases the chances of mistakes, delayed reactions, and unsafe decisions—precisely what you’re trying to avoid when you’re buoyant, moving, and thinking about gas management and safety checks.

So next time you’re weighing the social moment against the water moment, remember: keeping your head clear and your fluids balanced helps you stay in control, keep your buddy close, and enjoy the underwater time you’ve worked so hard to master. If you’ve already had alcohol, give yourself a little grace, hydrate, and simply plan for another day that’s all about learning, safety, and the pure joy of being in the water.

Want a quick recap? Here it is, in one line: alcohol increases dehydration and impairs judgment, so steer clear before a SCUBA outing, stay hydrated, and let your training guide your choices. That’s the surest path to safe, rewarding water time—every time you slip into your gear.