How Do Freedivers Sink?

How Do Freedivers Sink?

Freedivers sink in different ways depending on whether they are aiming for a maximum depth record, increasing the descent speed, descending with minimum effort, or simply enjoying the dive. Freedivers sink using weights like weighted belts and sleds, while some divers only rely on self-propulsion. 

If you have ever seen a freediver sink below the surface, then you would have realised how flawlessly they sink, and that freediving is one of the most thrilling watersports out there. 

While freediving requires a lot of dry training to master the sport, you also need to learn how to sink, because, let’s face it, how else are you going to explore the epic underwater world?

Freediving doesn’t require modern-day breathing equipment like scuba diving, so you are probably starting to question, how do you sink while freediving?

To answer that question, we will cover the following points:

  • Buoyancy and Freediving
  • Weights 
  • Things to Consider When Using Weight Systems
  • Self-Propulsion

But, wait… Before we get into the different ways freedivers sink, we must understand buoyancy underwater. 

Buoyancy and Freediving

Depending on the freediver’s lung capacity, air intake, body composition, and exposure suit, they will have a certain amount of natural buoyancy when freediving to overcome underwater. 

When freediving, you need to apply enough force to overcome your buoyancy, which requires physical effort or applying weight to your body. 

Underwater, there is far more pressure on your body than at the surface. For example, every 10m you descend, the pressure is doubled and the volume of gas inside your body is compressed. 

Air compression slowly reduces buoyancy until you reach a depth where gravity allows you to freefall without extra added weight.

When you are freefalling, you must focus on relaxation and equalization techniques you learned during your training. 

Freediver descending with fish swimming by

Weights

Freedivers use weights to sink, just like Scuba Divers. Adding weight to a freediver’s body allows them to descend and then maintain neutral buoyancy underwater. 

The main weighting systems freedivers use are weight belts and neck weights. If you are an experienced freediver, you may also use a weighted sled to displace your buoyancy underwater. 

It is not recommended to wear weights before you have had freedive training because it makes it harder to rescue you, adding risk.

In the beginning, you will likely start with a rubber weight belt fitted around your hips, similar to a weight belt in scuba diving. Rubber weight belts are used explicitly in freediving to allow space to breathe diaphragmatically and for easy weight distribution around your body. 

If you have mastered using weight belts, then why not try sinking with neck weights? Adding neck weights improves your trim, creating a more streamlined position during freefall in discipline training

Some freedivers only use neck weights, however, you need to have strong neck muscles to hold your head upright at the surface and you should have completed training in the pool. 

Whichever weight system you use, it must be quick release, so that you can quickly return to the surface in the event of an emergency. 

This is why weighted vests are not recommended for freedivers to sink. Weighted vests are usually not quick release, are loose-fitting, and create drag underwater. Spearfishers are often seen using them because they spend most of their time in relatively shallow water. 

If you are a very advanced freediver, you can use a weighted sled to sink. 

Weighted sleds pull you down as quickly as possible and require you to pull on a rope or use your arms or legs to ascend back to the surface.

They are primarily used during the No Limits and Variable Weight discipline for long sessions when you practise equalisation methods. 

Freediver descending on a line

Things to Consider When Using Weight Systems

When freedivers use weights to sink, there are a few things to consider such as gaining or losing weight before their last dive, the condition of their exposure suit, and what water conditions they are diving in. 

Before loading yourself with weights to help you sink freediving, you should consider the following:

  • Have you gained or lost any weight since your last freedive? Gaining and losing weight is natural, but in freediving, usually losing weight makes you less buoyant, therefore you will probably need to add fewer weights to sink. 
  • If you have recently gained muscle, you will need less weight. 
  • If you are freediving wearing an old wetsuit, it will be less buoyant because they compress over time. 
  • Has your freediving kit changed at all? Wearing different weight belts or fins can affect your buoyancy underwater. 
  • If you are diving in shallow water, you will need to add more weight than if you are using a line to descend deep into the ocean. 
  • Which freediving discipline are you completing? Some require more weight than others, and some freediving disciplines require no weight at all. 
  • What are the water conditions like? If you are diving in freshwater, you will require less weight than diving in salt water.

Self-Propulsion

Self-Propulsion involves the freediver using their arms or legs to descend instead of weights. However, self-propulsion consumes more oxygen, shortening their dive time and restricting them from reaching a deeper depth, which is why freedivers are more likely to use weights to sink. 

You can freedive without weights, giving you freedom from carrying as little freediving equipment as possible, however, it requires physical effort to sink during the initial descent underwater. 

You will need to use your muscle strength and proper swimming techniques to descend as deep as possible with no other sinking aids. This uses your valuable oxygen store more quickly, and therefore your dive time and depth will be more limited than using weights to sink. 

Getting yourself some decent freediving fins to aid with self-propulsion without weights is highly recommended!

If you are a tech freediver, you can employ a diver propulsion vehicle (DPV) to eliminate physical exertion and CO2 build-up, but you must complete proper training on how to use a DPV before using one underwater. 

Don’t Forget Your Dive Insurance!

Before you go out on any dive trip or holiday, it is essential to make sure you have insurance that covers you if something goes wrong. Check out our dive insurance article for more information.

Or go straight to these dive insurance company websites:

DiveAssure

Diver Alert Network (DAN)

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Final Thoughts

Freedivers usually sink using a weight system such as a weight belt, neck weight, or weighted sled, depending on how advanced they are and what they are aiming to achieve. 

While weights are the most common way for a freediver to sink, some freedivers also descend via self-propulsion until they reach neutral buoyancy. 

Whichever sinking method you use, you must never use weights until you have completed freedive training, and have a freediving instructor or experienced buddy nearby. 

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Darby Bonner

Darby is a marine biologist and PADI scuba diving instructor from the UK. With over ten years of diving experience, she has visited some of the best dive destinations in the world. Currently, Darby is living in Bali, Indonesia and regularly dives at some of the most beautiful dive sites in the Indian Ocean. Her passion for the ocean led her to study seals, publish a paper, and become a marine mammal medic. In the future, she hopes to complete her master’s in marine science, and of course, continue her love for teaching and diving!

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