Swimming underwater comes down to three things: holding a tight body position, moving efficiently, and managing your air. Whether you’re trying to glide across the bottom of a pool or swim a full length beneath the surface, the techniques are straightforward once you understand how your body behaves in water.
Start With the Streamline Position
The streamline is the foundation of all underwater swimming. Every meter you travel below the surface begins and ends with this shape. To set it up: stack your palms on top of each other with fingers together, squeeze your biceps behind your head, shrug your shoulders up so there’s no gap between them and the base of your skull, tighten your core, point your toes, and press your big toes together. Your body should look like an arrow.
The most common mistake is letting your head drift upward. Even a small lift of your chin creates a wall of resistance that kills your glide. Tuck your chin down and look at the bottom. If your arms won’t reach all the way behind your head, that’s fine. Focus on the head position first, because that’s where most of your drag comes from.
Practice this on land before you get in the water. Stand against a wall, lock in the streamline, and notice where you feel tension. Then try it in the pool by pushing off the wall and gliding as far as you can without kicking or pulling. The farther you travel on a single push, the better your position.
How to Propel Yourself Forward
Once you can hold a clean streamline, you have two main options for moving: a dolphin kick or an underwater pull sequence.
The dolphin kick (also called a butterfly kick) is the most common way to travel underwater. Keep your legs together and initiate the motion from your hips, not your knees. Your whole body should ripple in a wave, with the energy traveling down through your thighs, knees, and finally your feet. Small, fast kicks are more efficient than big, slow ones. Think of a whip snapping rather than a leg swinging.
For longer distances, competitive swimmers use an underwater pullout, which is a specific sequence borrowed from breaststroke. It works in five phases:
- Streamline: Push off the wall and hold your tight arrow shape until you begin to slow.
- Pull down: Sweep both arms simultaneously from overhead all the way to your hips in one powerful pull, like pulling yourself through a narrow tunnel.
- Recover the hands: Slide your hands back up along your body toward your chin, keeping your elbows tucked tight. This is sometimes called “the sneak” because you’re sneaking your arms forward without creating drag.
- Add a kick: Fire a single breaststroke kick (knees apart, feet snapping together) as your arms extend back into streamline.
- Break out: Angle slightly upward and take your first stroke as you reach the surface.
You don’t need to be a competitive swimmer to use this sequence. It’s the most efficient way to cover distance underwater on a single breath because each phase builds on the momentum of the one before it.
Control Your Buoyancy With Your Lungs
Your lungs are essentially built-in flotation devices. With a full breath, virtually everyone floats. With partially empty lungs, at the volume you’d have during a relaxed exhale, only about 7% of men float in freshwater. That difference matters when you’re trying to stay underwater.
If you find yourself floating back to the surface, you’re carrying too much air. Take a slightly smaller breath before submerging. You don’t want to exhale aggressively, because you need that air for oxygen, but reducing your lung volume even a little makes it dramatically easier to stay below the surface. Exhale slowly through your nose as you swim. This gradually decreases your buoyancy and lets you stay down longer without fighting against your own body.
Body composition plays a role too. Leaner swimmers tend to sink more easily, while higher body fat increases buoyancy. You can’t change this in the moment, but knowing it helps explain why some people struggle to stay down while others sink effortlessly.
Equalize Your Ears Early and Often
Even at the shallow end of a pool, you may feel pressure building in your ears as you descend. This happens because water presses on your eardrums, and the air space behind them needs to match that pressure. If you ignore it, you’ll get pain. If you keep ignoring it, you risk injury.
The easiest method is the Valsalva maneuver: pinch your nose shut, close your mouth, and gently blow as if inflating a balloon. You should feel a soft pop or click as air pushes into your middle ear. Do this before you feel pain, and repeat every time you go deeper.
A second option is simply swallowing with your nose pinched. This is called the Toynbee maneuver, and it works by using your tongue and throat muscles to open the tubes connecting your throat to your ears. Some people find this more natural than blowing against a closed nose.
More advanced swimmers use the Frenzel maneuver, which involves closing your throat, sealing your nose, and making a “K” sound with your tongue. This compresses air only in your nasal passages rather than using your whole chest, making it faster and more controlled. It takes practice but is worth learning if you plan to go deeper than a few meters.
Why You Can’t See Clearly Underwater
Without goggles, everything looks blurry underwater. This isn’t about opening your eyes (though pool chemicals can irritate them). The problem is optical. Your cornea, the clear front surface of your eye, provides about two-thirds of your focusing power in air. Water has a similar density to your cornea, so when water replaces air on the surface of your eye, that focusing power is essentially cancelled. The result is roughly the same blur you’d get from an extremely farsighted prescription.
Goggles or a mask fix this by trapping a pocket of air against your eyes, restoring the air-to-cornea boundary your eyes need to focus. If you’re serious about underwater swimming, goggles aren’t optional. They let you see where you’re going, judge distances, and navigate confidently.
Breathing Strategy and Safety
The biggest safety risk in underwater swimming is blacking out from low oxygen, and it almost always involves the same mistake: hyperventilating before a breath-hold. Taking many rapid, deep breaths before submerging feels like it loads you up with extra oxygen, but it doesn’t. What it actually does is flush carbon dioxide out of your blood. Carbon dioxide is the signal your brain uses to tell you it’s time to breathe. By artificially lowering it, you suppress the urge to surface. Meanwhile, your oxygen drops to dangerous levels without any warning. The result can be a sudden loss of consciousness underwater, which is how experienced swimmers drown in shallow pools.
A joint statement from the American Red Cross, USA Swimming, and the YMCA is blunt: hyperventilation before underwater swimming is dangerous and potentially deadly. The safe approach is to take a single, calm, deep breath before submerging. No repeated rapid breathing. No trying to “charge up.”
A few more practical rules that reduce risk:
- Never swim underwater alone. If you black out, you need someone on deck who can reach you within seconds.
- Stay in shallow water while learning. A pool depth of 3 to 5 feet gives you room to practice without the added pressure changes of deep water.
- Don’t do repeated long breath-holds. Each successive attempt depletes your oxygen reserves further. Rest fully between efforts, and limit how many you do in a session.
- Surface when you feel the urge. That first strong desire to breathe is your body’s built-in safety margin. Respect it.
Your Body’s Built-In Dive Response
When your face hits the water, your body triggers an automatic response inherited from other diving mammals. Your heart rate slows, blood vessels in your limbs constrict, and blood shifts toward your core organs. This reflex is strongest when cold water contacts the area around your nose and eyes, and it conserves oxygen by reducing how fast your body burns through its supply.
You don’t need to do anything to activate it. Simply submerging your face is enough. This is one reason why a calm, relaxed entry into the water works better than a panicked plunge. The more relaxed you are, the more efficiently this reflex works, and the longer your air supply lasts.
Putting It All Together
Start at the wall. Push off in a tight streamline with your chin tucked and toes pointed. Hold the glide until you feel yourself slowing, then begin your dolphin kick or pull sequence. Exhale slowly through your nose to manage buoyancy. Equalize your ears if you feel any pressure. Keep your movements smooth and compact, because thrashing wastes oxygen and creates drag.
In your first sessions, focus on distance over depth. Swim along the bottom of the shallow end rather than trying to dive deep. As your streamline improves and your comfort grows, you’ll find that the distance you can cover on a single breath increases surprisingly fast. Most of the improvement comes not from building lung capacity but from eliminating wasted movement and staying relaxed.