Pause at 15 feet for 3–5 minutes after a 40-foot ascent to protect against decompression sickness

What action is recommended during ascent after diving to 40 feet?

• A. Ascend directly without stops
• B. Perform a safety decompression stop at 15 feet for 3-5 minutes
• C. Continue ascending until reaching the surface
• D. Take a rest break at the surface

Answer: (B)

Performing a safety decompression stop at 15 feet for 3-5 minutes is highly recommended as part of a safe ascent procedure after a dive, particularly at depths like 40 feet. This practice allows nitrogen, which the body absorbs during the dive, to safely off-gas, thereby reducing the risk of decompression sickness, commonly known as "the bends." During a dive, the body absorbs nitrogen due to the increased pressure from the surrounding water. As the diver ascends, pressure decreases and nitrogen needs to be released back into the atmosphere so it does not form bubbles in the tissue, which can lead to serious injuries. The safety stop, typically made at about 15 feet, acts as a precautionary measure to help ensure that any remaining nitrogen is safely released from the bloodstream. This stop is important even for dives that may not require mandatory decompression stops according to dive tables or computers. It serves as an added safety measure, particularly for divers who may have residual nitrogen from previous dives. In contrast, ascending directly without stops or continuing straight to the surface can increase the risk of decompression sickness. Taking a rest at the surface is not a substitute for proper ascent procedures and does not address the necessary decompression management that should take

Here’s a simple truth many divers learn the hard way: going up isn’t just about getting closer to the surface. It’s about managing pressure, nitrogen in your tissues, and minimizing the chance of that nasty sensation people describe as “the bends.” When you’re at 40 feet, the ascent becomes a little choreography—one that rewards calm, patience, and a smart stop. And yes, the 15-foot stop for 3–5 minutes isn’t just for beginners. It’s a smart habit for divers at all levels.

Let me explain why that matters.

What happens to nitrogen when you go down and come back up?

Underwater, the ambient pressure is higher than at the surface. Gases dissolve into your blood and tissues more readily than they do on land. Nitrogen, which is inert and boring when you’re resting on land, becomes a little hungry for space when you’re under pressure. The deeper you go, the more nitrogen dissolves. As you ascend, pressure drops. If you shoot to the surface too quickly, those dissolved nitrogen molecules can form bubbles in your tissues and bloodstream. That’s decompression sickness, and it’s something you definitely want to avoid.

Now, where does that 15-foot stop fit into the picture?

You’ve finished the bulk of your ascent, coming up from a 40-foot depth. You could, in theory, keep rising. But the body doesn’t always agree with theory. A safety stop at about 15 feet gives your body a chance to off-gas the excess nitrogen gradually and safely. It’s a precaution, a pause that keeps you safer. The stop is commonly recommended for many dives, even when dive computers or tables don’t require mandatory decompression stops. Think of it as a margin of safety—a built-in cushion that acknowledges real life: slight variations in ascent speed, fatigue, and other tiny factors can change how your body handles nitrogen.

If you’re wondering, “Isn’t 15 feet a long way from the surface?” here’s the practical line: 3–5 minutes at 15 feet is short enough to be a routine part of your ascent, but long enough to let the off-gassing happen. You’re still moving toward the surface; you’re just taking a brief, deliberate pause to keep your body happy and healthy.

What should you actually do during the safety stop?

• Start the stop as you reach 15 feet. Don’t rush it. The purpose is to give your body a moment to off-gas.

• Breathe normally. Deep, controlled breaths help maintain a steady gas exchange and keep you relaxed.

• Stay still or very gently buoyant. You don’t need to swim laps here. A calm, stable position helps reduce the effort your body expends as it processes nitrogen.

• Keep an eye on your buddy and your depth. It’s easy to drift a bit; a quick glance at your depth gauge or dive computer helps you stay on target.

• Use a comfortable resting posture. A slight vertical trim or finding a neutral position in the water column keeps energy focused on your breathing rather than fighting buoyancy.

A quick word about the math and the mindset

If you like numbers, think of the stop as a deliberate, shallow pause to allow the off-gassing process to catch up with the dive reality. If you don’t love numbers, think of it as taking a breath between chapters of a story. You’ve just finished a chapter at depth; the stop gives you a moment to absorb and reset before the next chapter begins—the surface. Either way, the cue is simple: stop at 15 feet, for a few minutes, and breathe with purpose.

Common sense alongside the science

There are a few myths worth debunking, especially when you’re tired after a long dive. Some divers imagine that a rest at the surface replaces a proper ascent. It doesn’t. Resting at the surface is great for recovery, but it doesn’t address the decompression management you’re doing during the ascent. Others think, “If I’m not required to slow down by a table or computer, I’ll skip the stop and save time.” The truth is: safety stops aren’t about saving time; they’re about saving you from potential problems that can ruin your day—or your week—underwater.

How this fits into real life on the boat or shore

On most dives, people naturally have a moment after surfacing to relax, check air, and share a quick debrief with their buddy. The safety stop is easiest when you treat it as part of the ascent, not a separate task. If you’re with a buddy, you can tag-team the process: one person stays a few breaths at 15 feet, the other keeps an eye on instruments and signals. If you’re solo training or in a guided dive, your instructor or dive guide will emphasize the stop as part of your ascent protocol. Either way, the habit is the same: plan the stop, honor the stop, and trust the calm.

What about the other choices people sometimes consider?

• Ascend directly without stops? That’s the fastest route to trouble if nitrogen off-gassing isn’t fully managed. In most situations, it’s simply not worth the risk.

• Continue ascending until the surface? Again, the need to decompress or slow down the ascent becomes more pressing as depth increases. The body doesn’t appreciate a speed-run to the surface after a fresh 40-foot dive.

• Take a rest at the surface? Resting is valuable for recovery and safety checks, but it doesn’t replace the stop. It’s part of the routine, not a substitute for decompression safety.

Practical tips that fit into a typical dive day

• Plan for the stop before you start the ascent. If your dive plan is written with a safety stop in mind, you’ll be less likely to skip it when the adrenaline starts to wear off and you’re thinking about the boat ride back.

• Use a reliable buoyancy control device (BCD) to hover at 15 feet. A small amount of buoyancy control goes a long way here—keep it steady, not strenuous.

• Stay with your buddy. The stop becomes easier and safer when you’re not drifting apart or chasing each other’s bubbles.

• Be mindful of workload. If you’ve had a particularly strenuous dive or you’re feeling fatigued, give that stop a bit more attention. A longer 3- to 5-minute pause can be worth it.

• Hydration and energy matter. A quick drink of water before the stop, if you’re allowed by your plan, helps your body manage the stress of the dive day. Just don’t overdo it.

A note on symptoms and aftercare

If, after your ascent, you notice numbness, unusual joint pain, dizziness, headache, or weakness, those could be signals that something isn’t quite right. If you feel anything like that, seek medical assessment promptly. The safety stop is preventive, but it’s not a guarantee against all decompression issues. Your well-being comes first, always.

Bringing it back to the core idea

So, when you’ve been at 40 feet and you start your ascent, the recommended action is clear: perform a safety decompression stop at about 15 feet for 3–5 minutes. It’s a small, practical step that yields a big safety payoff. It’s one of those habits that makes good divers reliable—and it gives you a quiet confidence when you’re breathing through your regulator, watching the urge to rush melt away, and savoring the moment between depth and surface.

If you ever wonder whether this “small” pause is worth it, think of it as a pause with a purpose. The ocean doesn’t rush, and your body shouldn’t have to, either. The stop honors the physics of breathing underwater, honors your training, and helps you come back to the surface in good shape to enjoy the rest of your day, your week, and your next dive adventure.

A final thought to carry with you

Diving isn’t only about the thrill of the moment under water. It’s also about stewardship—of your body, your buddy, and the mysterious, magnificent environment you’re exploring. The 15-foot stop isn’t a rule to be followed mindlessly; it’s a careful practice that keeps that environment, and you, safe for more stories, more discoveries, and more shared breaths under the surface. After all, the sea has a way of rewarding patience with clarity, color, and a deeper sense of freedom. And isn’t that what you signed up for from the start?