How to Master Freediving Buoyancy: The Science Made Simple
July 23, 2025
Buoyancy control is one of the most essential - and often underrated - freediving skills. Whether you are gliding effortlessly at depth or maintaining a streamlined ascent, mastering neutral buoyancy helps improve efficiency, enhance relaxation, and conserve oxygen. But how exactly do you achieve perfect freediving buoyancy?
Unlike scuba divers who rely on air to adjust buoyancy, freedivers must fine-tune it through lung volume, body position, and proper weighting. A well-balanced freediver typically reaches neutral buoyancy around 10–12 meters during deep dives—neither sinking nor floating. Learning how to control this balance can make your dives smoother, safer, and more enjoyable.
In this guide, we will break down the physics of freediving buoyancy, the factors that affect it, and the techniques you can use to achieve and maintain neutral buoyancy in freediving.
The Physics of Buoyancy in Freediving
Buoyancy is governed by Archimedes’ Principle, which states:
An object submerged in a fluid experiences an upward force equal to the weight of the fluid it displaces.
In freediving, your buoyancy is influenced by several key factors: lung volume, body composition, wetsuit thickness, weighting, and whether you are diving in saltwater or freshwater. As you descend, these variables shift—lungs compress, wetsuits lose lift—making freediving buoyancy a constantly changing force that you must learn to manage throughout the dive.
The Three States of Freediving Buoyancy
- Positive Buoyancy – At the surface, your body floats because the upward force exceeds your weight.
- Neutral Buoyancy – You reach a point—typically around 10–12 meters—where you neither rise nor sink.
- Negative Buoyancy – Deeper down, your compressed lung volume reduces your buoyant lift, and you begin to sink with little effort.
Freedivers naturally transition through all three states in a single dive. Understanding how and when these changes occur is essential for efficient movement, energy conservation, and freediving safety.
Factors That Influence Buoyancy in Freediving
Freediving buoyancy is dynamic—it changes throughout a dive based on your equipment, environment, and body. By understanding how these factors interact, you can better control your movement, reduce effort, and stay safe underwater.
1. Lung Volume and Depth-Dependent Buoyancy Changes
Your lungs act as a built-in buoyancy compensator. At the surface, fully inflated lungs create positive buoyancy, helping you float easily. As you descend, water pressure compresses the air in your lungs, reducing volume and buoyancy.
Most freedivers reach neutral buoyancy between 10 and 12 meters, where they no longer rise or sink. Below this, negative buoyancy kicks in, allowing for a smooth, effortless descent. On the way back up, lung expansion restores buoyancy—making the final few meters feel lighter and more buoyant.
2. Wetsuit Thickness and Compression
A freediving wetsuit traps air in the cells of neoprene material, making it naturally buoyant. However, as you descend, the material compresses, reducing its buoyancy.
- Thicker wetsuits (5mm-7mm) provide more buoyancy at the surface but lose buoyancy at depth.
- Thinner wetsuits (1mm-3mm) offer more stable buoyancy across different depths.
A well-weighted freediver accounts for wetsuit compression and adjusts their neutral buoyancy depth accordingly.
3. Weighting for Proper Balance
Weights help fine-tune your freediving buoyancy so you can descend with control and ascend with ease. The goal is to be:
- Positively buoyant at the surface, even after a full exhale
- Neutrally buoyant around 10–12 meters
In disciplines like dynamic apnea or deep freediving, neck weights can help improve your body position, reduce drag, and prevent head tilt—making you more streamlined and energy-efficient throughout the dive.
The Role of Buoyancy in the Freefall Phase
One of the most rewarding parts of a freedive is the freefall—the quiet, weightless glide after neutral buoyancy sets in. Once you become negatively buoyant (usually after 10–12 meters), gravity takes over and you can stop kicking, saving energy and oxygen.
By mastering your freediving buoyancy leading up to this point, you can enter the freefall in a streamlined, relaxed state, letting your body descend with minimal effort. Learning to trust this phase and release tension can be transformative for both performance and enjoyment.
Saltwater vs. Freshwater: How Water Type Affects Your Freediving Buoyancy
Water density plays a key role in how buoyant you are. Because saltwater is denser than freshwater, it provides more lift—meaning you will need more weight when diving in the ocean than in a lake or pool.
If you are transitioning between different environments, always perform a buoyancy check before your dive. Even small changes in water type can significantly affect your weighting and control underwater.
How to Achieve and Maintain Neutral Buoyancy in Freediving
The key to mastering freediving buoyancy starts before you even descend—with a proper buoyancy check at the surface. To perform one, float upright in a relaxed vertical position and exhale fully. Ideally, the waterline should sit around your eyebrows.
- If you sink too quickly, you are likely overweighted.
- If you struggle to submerge, you may need to add a little more weight.
Always adjust your weight based on wetsuit thickness, water type, and diving conditions. Getting this right helps you maintain a smooth balance between positive, neutral, and negative buoyancy throughout the dive—reducing effort and increasing comfort from start to finish.
Common Buoyancy Mistakes (and How to Fix Them)
Even experienced freedivers can get buoyancy wrong from time to time. Here are a few common issues:
- Overweighting – Causes rapid descents and tiring ascents.
Fix: Re-check your surface buoyancy with a full exhale before diving. - Underweighting – Makes it hard to descend and burns energy early in the dive.
Fix: Add weight gradually until you reach neutral buoyancy around 10–12m. - Ignoring wetsuit compression – Leads to unexpected shifts in buoyancy at depth.
Fix: Practice dives at different depths and adjust weights to your wetsuit type.
Training Tips to Improve Your Buoyancy Awareness
Like any freediving skill, buoyancy control improves with consistent practice. One of the simplest ways to build awareness is by doing slow, relaxed dives in shallow water. This allows you to observe how your freediving buoyancy changes with depth—especially as your lung volume compresses.
Using a dive buddy to film your descent and ascent can be incredibly helpful. Watching yourself on video may reveal subtle posture or weighting issues that are hard to notice in the moment.
Another useful habit is to practice exhaling at the surface to check your positive buoyancy. This helps you fine-tune your weight setup and ensures you are not overweighted before you dive.
With time and repetition, you will develop a more intuitive sense of how your body behaves underwater—and how small adjustments can lead to smoother, more efficient dives.
Take Control of Your Buoyancy, Transform Your Dives
Mastering neutral buoyancy is one of the most valuable skills you can develop as a freediver. It allows for smoother descents, more relaxed ascents, and greater oxygen efficiency—key ingredients for safe and enjoyable dives.
By understanding how factors like lung volume, wetsuit compression, weighting, and water type influence your freediving buoyancy, you can fine-tune your setup and technique to move with confidence and control in any environment.
Want to sharpen your skills even further?
Join an SSI Freediving Course near you and take your training to the next level.