I do not want to arrive at the descent point already breathing hard, and I do not want the return to shore after a dive to become another strenuous portion of the day. Good surface swimming is mostly about establishing enough buoyancy, finding a sustainable body position, and moving at a pace that leaves plenty of reserve.
Get Buoyant Before You Start Swimming
Put enough gas into the BCD that you can stop using your arms and legs without sinking. In relatively calm water, I normally want the waterline somewhere around my chin, not enough inflation to lift my neck and shoulders well above the surface.
If you have to kick simply to keep your mouth clear of the water, the BCD is not doing enough work. If you are inflated so aggressively that your upper body is being pushed high out of the water and the equipment feels unstable, you have probably gone too far in the other direction.
The correct amount depends on weighting, exposure protection, cylinder, BCD design, and body position. Inflating and Deflating Your BCD at the Surface covers that relationship in more detail, including why a heavily inflated wing can feel awkward when the diver insists on remaining upright.
Before starting the swim, identify where you are actually going. Find the boat, shoreline feature, descent float, dock, or other reference you intend to use, check where your buddy is, and look at what the wind and current are doing before you settle into the swimming position.
Swimming on Your Back
Once the BCD is supporting me, I roll onto my back and let the fins provide the propulsion. My face is completely out of the water, breathing is unrestricted, and I do not need a regulator or snorkel in my mouth.
A relaxed flutter kick works well for me. I use a pace that feels sustainable for considerably farther than I expect to travel, because covering the first part of the swim quickly has little value if I spend the second half recovering from it.
The main compromise is visibility. I am not staring continuously in the direction of travel, so I periodically check my heading and make whatever correction is necessary. As I approach a boat, descent line, shoreline obstacle, or other place where precise navigation matters, I check more frequently and may eventually change position altogether.
For a meaningful distance in ordinary conditions, I find that periodic navigation checks are a much smaller inconvenience than spending the whole swim face-down.
When I Swim Face-Down
I turn face-down when I actually need to see continuously where I am going or what is below me. That may happen during the final approach to a descent point, while looking for a submerged feature, near a boat ladder, or when moving through an area where I want constant visual awareness ahead.
When I do that, I normally use the regulator. I do not carry a snorkel as part of my regular scuba configuration, and the reasons are covered in Do You Really Need a Snorkel for Scuba Diving?. If you choose to carry one anyway, Using a Snorkel at the Surface covers how to use it correctly.
For a short face-down swim, regulator gas consumption is not something I worry about. Using a modest surface breathing rate of about 0.7 cubic feet per minute, an AL80 holding roughly 77.4 cubic feet at 3,000 psi loses about 27 psi per minute. Five minutes of surface breathing is therefore roughly 135 to 140 psi, which I consider negligible in an ordinary recreational dive.
If the surface swim is long enough that the gas consumption becomes meaningful and conditions permit it, I roll onto my back and stop using cylinder gas entirely.
Use a Kick You Can Sustain
The objective is useful propulsion without exhausting the legs. A surface swim is a poor place to turn an ordinary flutter kick into a sprint, particularly before a dive when the energy will be more useful underwater.
I let most of the movement come from the hips while allowing the knees and ankles to move naturally. Locking the legs straight is unnecessary, while an exaggerated bicycle kick tends to burn energy without producing much useful movement.
The fins should be moving water rather than simply throwing spray into the air. If the legs begin to fatigue, slow the pace, adjust the kick, or change position for a while rather than insisting on maintaining the exact same motion.
Over a genuinely long swim, changing how the legs are working can make a noticeable difference. The goal is to arrive with energy left rather than demonstrate perfect surface-kick form for the entire distance.
Navigating While Swimming on Your Back
Choose a reference that is large enough to reacquire quickly. A boat, flag, building, tree line, buoy, dock, or distinctive shoreline feature works better than something small that disappears every time you lie back.
I check the reference periodically, correct my direction, and return to a relaxed swimming position. There is no need to hold the head awkwardly forward throughout the swim merely so I can watch the destination continuously.
Wind and current can produce substantial sideways movement without making that movement obvious from the diver's perspective. Each time I check my heading, I am also checking whether I am actually gaining ground in the direction I expected.
As the destination gets closer, those checks naturally become more frequent. If I need precise control during the final approach, I roll face-down and watch where I am going.
Current Can Change the Route
If I am kicking steadily and making almost no progress, increasing the effort is not automatically the right answer. A different route may lead toward weaker current, protected water, a more practical shoreline exit, or a boat current line that makes the entire swim easier.
Look at your actual movement relative to fixed references rather than judging progress by how hard you are kicking. A strong current can make a diver feel busy while accomplishing almost nothing.
If assistance is available, signal before the swim becomes an exhaustion problem. Conserving energy and allowing a boat or another diver to help is preferable to using most of your reserve fighting water that is stronger than expected.
Rip currents require a different response from an ordinary lateral dive-site current. If one is carrying you away from shore, trying to overpower the strongest part directly can exhaust you quickly. Maintain flotation, move out of the strongest flow, and then work back toward shore rather than treating the shortest line to land as the only possible route.
Cramps and Fatigue
A calf cramp is a reason to stop swimming, not something to push through. Let the BCD carry your weight, extend the affected leg, and pull the fin tip or toes toward you until the calf begins to release.
Give the muscle enough time to settle before immediately returning to the same effort. If your buddy can help for a while, use that help rather than converting a temporary cramp into complete fatigue.
General exhaustion should be handled the same way. Stop, make sure the BCD is providing comfortable positive buoyancy, and rest before deciding whether continuing the swim still makes sense.
If I am tired while swimming face-down, the regulator stays in while I recover. Once I am able to roll onto my back comfortably, I can breathe normally and stop using cylinder gas while the BCD does the work of keeping me afloat.
Practice With the Equipment You Actually Dive
A twenty-foot pool demonstration does not tell you much about what a surface technique feels like after several minutes in full scuba equipment. Swim far enough to settle into a real rhythm and notice what your equipment is doing.
Practice on your back until you know how much BCD inflation puts the water around your chin, how your fins feel from that position, and how frequently you need to check direction. Then swim the same distance face-down and compare the effort and breathing options.
Different exposure suits, fins, cylinders, and BCD designs can change the experience substantially, so the useful answer is the one you discover in your actual configuration. For me, that answer has been consistent for years: I surface swim on my back unless I have a specific reason not to, because it keeps my airway clear, uses no cylinder gas, and makes a long surface swim feel like very little work.