We plan and execute every recreational dive around gas and time constraints. On a relatively shallow reef dive — or when using nitrox — we often end the dive based on gas consumption rather than time underwater. Dive instructors and guides always seem to be “good on air,” but how do they do it? And how can you make your air last longer when diving?

Much like some other physical traits, some people simply have better gas consumption. You can’t change the laws of physics and it takes more energy to propel a larger person than a smaller person. However, there is always room to improve. Essentially, you can make your air last longer in any of three broad and overlapping categories: equipment, knowledge and skills, and personal preparation.

Equipment

• Only take what you need for the dive. Every accessory attached to your BCD is additional weight and drag, making you less streamlined. As a consequence, you’re more likely to expend energy moving through the water.
• Keep your equipment well-maintained. Get your regulators serviced in accordance with manufacturer instructions by a trained technician. Be mindful of your hose lifespan and condition to help ease breathing and aid avoid losing gas through leaks. Make sure your BCD adds and releases air smoothly, allowing you to make small adjustments easily. Check your fins for splits and fraying. Any degradation in performance means you’ll expend more energy to propel yourself or achieve neutral buoyancy. Consequently, you’ll breathe more gas.
• Make sure your equipment is the right size. Ill-fitting equipment will only compromise your movement in the water. For example, a BCD that’s too large — allowing the cylinder to roll around on your back — may leave you struggling to maintain balance during the dive and expending unnecessary energy. Poorly fitting fins will compromise your finning technique and increase your gas consumption. Get professional advice and, if possible, buy your own equipment rather than trying to adapt to different rental equipment on every dive trip.
• Take what is suitable for the dive. Smaller snorkel-style full-foot fins won’t be able to cope with a moderate current at a challenging dive site. Taking the other extreme, a bulky drysuit and weighty jet-fins are unnecessary on a tropical reef. Research before you go and wear the optimum equipment.
• Stay warm. A body fatigued by cold will use more energy and more gas. Wear the proper exposure protection for that environment at the end of those dives — not the beginning — and at the deepest These are the times when your body is more vulnerable to temperature changes and you’re likely to discover that you really should have packed that thicker exposure suit or hood.

Knowledge and skills

• Improve your general diving knowledge. Take continuing education courses. Listen to more-experienced divers and seek out their advice. Put the knowledge you gather into practice in the water. That may include a formal class, such Peak Performance Buoyancy, or something informal, such as a conversation with an experienced local guide. He or she may recommend a certain route around a wreck or reef to avoid fighting current or water movement. Increasing knowledge in either way can potentially improve your gas consumption.
• Research the environment where you’re about to dive. Knowing the water temperature, techniques and procedures will help you physically prepare in terms of fitness and equipment selection. Preparation can simultaneously help you visualize your dives and be more relaxed about the upcoming dives before you get anywhere near the water. Your gas consumption will likely improve as a consequence.
• Work on your buoyancy. Neutral buoyancy is the cornerstone of good diving. Spend some time perfecting your weighting. Practice making smooth descents and ascents. Hone your skill level to the point that neutral buoyancy is your default position and — if you stop finning — you simply stop moving forward. Finning should have no bearing on your depth in the water column. The less energy you expend maintaining position, the less gas you will consume.
• Work on your trim. New divers tend to be more upright in the water, as if they’re riding an invisible unicycle. Relax to the point that you’re virtually horizontal for 99 percent of your dive, other than your initial descent and ascent.

• Slow down. While you may occasionally need to pick up the pace to turn a corner against a current or deal with an issue, most of your dive should be slow and smooth. The dive is about the journey, not the destination. Just like driving a car, if you’re easy on the throttle, you’ll consume less fuel.

• Stay shallower where possible. Think back to your initial theory training. Your gas consumption, all other things being equal, is a factor of the atmospheres of pressure you’re under. Unless there’s a specific reason to go deeper, such as a wreck or other attraction, stay a little shallower. If your planned maximum depth is 100 feet (30 m), spend only the time you need there to get that photo you’re after. Then, gently drift along the reef at a shallower depth to conserve gas.
• Breathe slowly, deeply, and easily. Do not force it. Each inhalation and exhalation should be gentle and unflustered, as if you’re following your breath in a meditation. Relaxed as if you’re in a favorite comfortable chair. Many novice divers report two sensations related to regulator use: an aching jaw from excitedly gnawing on the mouthpiece and a dry throat as they guzzle the pure, filtered air. Slow it down.

Personal preparation

• Fitness is key to diving. You needn’t be an Olympic athlete and, for most simple, tropical, reef dives, you’ll be expending minimal energy. Nevertheless, even in simple conditions, it’s common to see less-fit divers using a larger cylinder to complete the same dive as a fitter and more-efficient diver. The harder the dives, the more critical your fitness becomes. If you’re diving in challenging conditions or circumstances change during a dive — for example, the waves and current have become more severe or your buddy has an issue — you must be fit enough to handle it. Good physical fitness means your pulse and breathing rate will remain reduced even when dealing with an issue. Exercise regularly and maintain your weight at healthy levels to reduce your gas consumption.
• Rest properly for your dives. If you’re sleep-deprived, dehydrated or haven’t eaten properly, your body simply won’t perform as well. In addition, factors such as dehydration put you at higher risk for problems such as DCS. Strike a balance between enjoying your dive trip on land and being well-prepared for the dives. Get enough sleep and eat and drink sensibly. Give your body the tools it needs to be physically prepared for diving.
• Be on time for the briefing or boat departure. If you’re late or flustered before you enter the water, you’re much more likely to have a raised pulse and increased breathing. Arrive at least five minutes before a briefing or 15 minutes before a boat departure, with your gear checked and nitrox analyzed.

• Plan the dive. Dive the plan. A significant proportion of a good dive comes down to preparation and confidence before you enter the water. Sound dive planning helps you know exactly what lies ahead. Take a slate to dive briefings if you’re not a regular diver in the area; note entry, exits and dive procedures, maximum depths, no-stop times at depth, landmarks, hazards and points of interest. Visualize the dive in your mind before you enter the water and discuss your plan with your buddy. The clearer and calmer you before the dive, the more relaxed you’ll be and the more likely you’ll have reduced gas consumption.

While great gas consumption does not always correlate to being a great diver, improving your preparation and skills for each dive will more than likely help you improve your gas consumption and extend your dives.