Underwater Swimming: Mastering Buoyancy, Propulsion, and Safety

How to stay underwater when swimming?

Mastering the ability to stay submerged while swimming involves a strategic blend of understanding buoyancy, optimizing body density through breath control, and employing efficient hydrodynamic techniques for propulsion and stability.

Understanding Buoyancy and Density

To effectively stay underwater, it's crucial to grasp the fundamental principles of buoyancy and how they apply to the human body.

• Archimedes' Principle: This principle states that an object submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object. For humans, if the buoyant force is greater than your body weight, you float; if it's less, you sink.
• Body Composition: Human body density varies. Muscle tissue is denser than fat tissue, meaning individuals with a higher muscle-to-fat ratio tend to be naturally less buoyant (more likely to sink) than those with a higher fat percentage.
• The Lungs as Flotation Devices: Your lungs, when filled with air, act like natural air bags, significantly increasing your overall buoyancy. Air is much less dense than water, making a lungful of air a major factor in keeping you afloat.

The Role of Breath Control

Strategic breath management is perhaps the most immediate and impactful way to control your buoyancy.

• Full Exhalation: The most direct method to decrease buoyancy is to fully exhale before submerging. Expelling air from your lungs increases your body's overall density relative to the water, making it easier to sink and stay down.
• Partial Exhalation for Depth Control: For maintaining a specific depth or performing tasks underwater, you might not need a complete exhalation. A partial exhalation can provide enough negative buoyancy to stay submerged while still retaining some air for comfort and oxygen supply.
• Diaphragmatic Breathing: Practicing deep, diaphragmatic breathing can improve lung capacity and breath-holding ability, which, while not directly related to staying underwater, is essential for extended underwater activity.

Optimizing Body Position and Streamlining

Hydrodynamics plays a critical role in minimizing resistance and maintaining an underwater path.

• Streamlined Position: To move efficiently underwater and reduce drag, adopt a streamlined "pencil" or "Superman" position. This involves extending your arms straight overhead, hands clasped or stacked, and keeping your head neutral, aligned with your spine. Point your toes to further reduce surface area.
• Core Engagement: A strong, engaged core is vital for maintaining a rigid, streamlined body position. This prevents wobbling or sagging, which would increase drag and make it harder to hold your depth.
• Head Position: Keep your head in line with your spine, looking down or slightly forward. Lifting your head can break your streamlined form and cause your legs to drop, increasing drag and upward lift.
• Tuck or Pike for Initial Descent: If you're struggling to get fully submerged, a brief tuck (knees to chest) or pike (hips bent, legs straight) can momentarily decrease your volume and help you sink, after which you can extend into a streamlined glide.

Effective Underwater Propulsion Techniques

Once submerged, efficient propulsion helps you maintain momentum and control your depth.

• Dolphin Kick: This powerful, undulating movement originates from the core and hips, propagating through the legs and feet. It is highly effective for underwater propulsion, mimicking the movement of a dolphin's tail. Ensure the kick is continuous and fluid, with pointed toes.
• Underwater Pulls (Freestyle/Breaststroke):
  • Freestyle: After a push-off, a strong, deep freestyle pull can be used for initial propulsion before transitioning to a dolphin kick. The hands pull deep, almost to the thighs, before recovery.
  • Breaststroke: The underwater breaststroke pull-down is a powerful, regulated move. After pushing off, perform one long, deep pull with your arms, bringing them down past your hips, followed by a powerful breaststroke kick. This is often used for race starts and turns.
• Efficiency Over Power: Focus on smooth, continuous movements that minimize turbulence. Jerky or inefficient movements waste energy and create drag, making it harder to stay submerged.

Training for Underwater Performance

Consistent training can significantly improve your ability to stay and move underwater.

• Underwater Glide Drills: Practice pushing off the wall into a perfect streamlined position and gliding as far as possible without kicking or pulling. This builds body awareness and streamlining efficiency.
• Dolphin Kick Drills: Focus on isolated dolphin kicks, both on your front and back, to develop power and fluidity from your core.
• Breath-Hold Training (with caution): Under strict supervision and in a controlled environment, gradual breath-hold exercises (e.g., static apnea drills) can increase your comfort and capacity for being underwater.
• Strength and Flexibility: Develop core strength for stability and leg power for kicking. Ankle flexibility (dorsiflexion) is crucial for an effective dolphin kick.

Safety Considerations for Underwater Swimming

Underwater swimming, especially breath-hold activities, carries inherent risks. Safety must always be your paramount concern.

• Never Hyperventilate: Do not take multiple deep, rapid breaths before going underwater. This reduces carbon dioxide levels in your blood, which is your body's primary signal to breathe. This can lead to Shallow Water Blackout (SWB), where you lose consciousness underwater without warning, often in shallow water, and can be fatal.
• Always Swim with a Buddy: Never practice underwater swimming or breath-holding alone. A trained spotter should always be present and attentive.
• Know Your Limits: Do not push yourself beyond your comfortable breath-hold capacity. Listen to your body's signals.
• Avoid Competitive Breath-Holding: This practice is extremely dangerous and has led to numerous fatalities.
• No Diving into Unknown Depths: Always confirm the depth of the water before attempting to stay submerged or dive.

Conclusion

Staying underwater while swimming is a skill that combines an understanding of physics, precise body control, and efficient movement. By mastering breath control to manage buoyancy, perfecting a streamlined body position to reduce drag, and employing powerful yet efficient propulsion techniques like the dolphin kick, you can effectively navigate and remain submerged. Always prioritize safety, especially when practicing breath-hold techniques, and ensure you are never alone when engaging in underwater activities. With consistent practice and a scientific approach, you can enhance your underwater capabilities for fitness, performance, or simply the enjoyment of the aquatic environment.