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Spearfishing & Freediving Safety Tips

The Committee is made of passionate Spearfishers and Freedivers.  Several of the Committee attended the 2015 AIDA 2 and 3* courses and during this time we discussed the idea of sharing  some of the safety tips learned through experience, AIDA and being involved in the freediving scene.


To this end we have collated some tips covering some of the more common areas that could aide in mitigating some of the risks involved with Water Apnea activites and Spearfishing.  


It should be noted that this is only a subset of some of the risks and strategies to mitigate these, it is not a complete list of all risks to be aware of when spearfishing nor is it a substitute for diving within your limits, or with a buddy.


Dive Flag:


An actual incident that occurred a while back: no flag and diving off a popular beach.  A jetski operator came in at speed and went into a tight turn around the buoy just as the diver surfaced.


This could have ended in disaster. Who was at fault?


This is simple, buy a dive flag and put it on your float or float boat and use it always… no exceptions.


Boaties by law, cannot exceed have an obligation to slow to 5knots when within 200m of a dive flag, we have an obligation to use one so that they know to do this. Without this simple addition the boat owner will have no idea he’s about to encounter a diver.




Ideal weighting depends on what depth you are diving to and what you are targeting: targeting snapper in the shallows often calls for more weight so that you can more easily hug the rocks and weed when sneaking up on that 20 pounder. For deeper diving it is important to not have too much weight as this will make your ascent much harder and potentially riskier. When diving deeper, for example working a weedline, at a minimum you should ensure you are buoyant from at least 10m, more if diving even deeper.  


Breathe up:


Possibly one of the most important areas is the pre-dive breathe up.  To ensure adequate recovery between dives, when diving shallower than 30m, as a conservative rule double the duration of your dive for the breath up on the surface.  


In addition to a decent amount of time to recover, it is very important to ensure you also aren’t hyperventilating. Hyperventilation is the process of breathing faster or deeper than you need to, beyond what you require to maintain your current homeostasis (e.g. maintaining your balance of acid and alkalinity).


Why is this bad? In addition to elevating your heart rate, hyperventilating also lowers the levels of C02 in your bloodstream, which can reduce your ability to detect when your oxygen levels are getting critically low.(think of this like making your car’s fuel tank appear more full than it actually is; everything appears fine until you run out of fuel). Additionally, the lowering C02 levels also impacts with your blood’s alkalinity and this can inhibit your body’s ability to release oxygen to where it is most needed making a blackout much more likely to occur.


To avoid hyperventilating, be conscious of how your breathing on the surface: breaths should be relaxed. Freediving courses suggest that the exhale should ideally be around twice the duration of the inhale time. Be mindful of how you are breathing when in conditions that require regular clearing of the snorkel (e.g. in chop or swell), you could be hyperventilating without even realising it.




As we dive deeper the volume of air we have in our lungs, sinuses and middle ear decreases. This is caused by the increase of pressure. The increase in pressure is so significant that in salt water a fully inflated balloon on the surface will shrink to 50% of its original size at 10m (see Boyle’s law for more on this one). What this all means is that we need to equalize the aforementioned air spaces to offset the reduction of volume due to the increase in pressure.  To avoid injury, equalising should be performed frequently and before any pain is felt.  If you experience any pain, abort the dive and try again after an adequate surface recovery.  

There are several techniques you can use to equalize the two most common options are the Valsalva and the Frenzel.  The former requires air to be pushed up from the lungs into the eustachian tubes and other air spaces. The other method of equalising is called the Frenzel manoeuvre; this involves using your tongue to piston air to where it is needed to offset the pressure change.  The Frenzel is superior to the Valsalva in many ways and once learned it can be performed more easily and more frequently.  


Barotrauma (Injury from pressure):


In addition to equalising there are other risks to be aware of when diving deeper.  One of the other key risks occurs when diving at or below Residual volume.


Not sure what Residual volume is? Exhale all your air until you can’t exhale anymore; now imaine you have dived to a depth where your full lungs on the surface have compressed to this same point, this is your Residual Volume. For an average person this normally occurs at around 30m.  


Freediving at close to Residual Volume, or deeper brings with it a risk of something called lung squeeze. This is where the pressure at depth causes walls of your lungs to stick together, causing damage as they peel apart. The risk of lung squeeze increases if the diver is cold or makes sudden movements (particularly ones that can cause stretching of the intercostal muscles and areas surrounding the lungs).  


Some of the key steps to avoid lung squeeze is to increase depths gradually, ensuring you are adequately warm and minimising movement that will stretch the muscles surrounding the lungs at depth. Stretching prior to getting in the water is also thought to decrease this risk.


Shallow Water Blackout:


A Shallow Water Blackout (SWB) is where a diver blacks out near the surface after diving to depth.


There are a few factors in play that cause this, but in short,  the consumption of oxygen at depth becomes more pronounced as the partial pressure and therefore the % of oxygen also decreases.


Basically this means you don’t notice you are short on oxygen until nearer the surface. In addition to this the pressure change and re-expansion of the lungs can also absorb oxygen from the other vital parts of the body such as the brain, further exacerbating the decrease in oxygen levels. The result of all this is that the likelihood of blackout is the greatest on the ascent, near the surface.


To mitigate this risk, always ensure you dive within your limits, (I.e. with reserve capacity) and be prepared to ditch your weight belt if you need to. Your buddy should also be especially vigilant and watching your dives during this stage of your dive, ready to help if needed.  


Recovery Breaths:


On the surface after a dive you should perform a passive exhale (relaxed breath out, rather than a forced one) and a rapid inhale. Ideally this should be performed several times to ensure you are getting oxygen to where it is needed as quickly as possible. Your buddy should continue to watch you during this phase as there is still a risk of blackout even up to, and potentially beyond, 30 seconds after your dive.


What to do in the event of a blackout:


In the situation where a blackout occurs, having a buddy is crucial.  If the blackout occurs at a depth at which your buddy is capable of rescuing you safely, they will need to swim you back to the surface.  One of the recommended methods of swimming a diver to the surface is by supporting the neck/back of the head with one hand and clamping the mouth shut and holding the chin with the other hand.  Arms should be extended so that the unconscious diver is clear of the rescuer’s fins.


Once at the surface it is essential that the unconscious diver’s airways are kept clear of the water. The mask should be removed from the unconscious diver and the rescuer should blow on the diver’s face just below the eyes; they should then tap the same place as where they blew and then talk to the person encouraging them to wake up. (These steps are often referred to as Blow, Tap, Talk).  


In the event the person does not return to consciousness within 15 seconds they should be removed from the water and CPR should be commenced.  Once conscious they should stop diving, and, if water was swallowed, seek medical assistance to avoid secondary drowning.


Rescuing someone from a blackout is definitely something that should be practiced in a controlled environment and ideally with someone experienced who can demonstrate the technique (e.g. a club or on a course).  This is something you should strongly encourage your buddy to practice as frequently as possible, it could be your life they are saving!


A short demonstration of the rescue technique can be viewed here


Other Spearfishing Tips:


  • If freediving with an attached catch bag (as sed for collecting scallops), empty it before it becomes difficult to ascend.

  • Collecting Crayfish – don’t swim into caves and don’t get your arm caught. if you’re getting short on breath let it go.

  • Spearfishing – Weed will tangle you and so will your float line. Make sure you path is clear. Float line across the back of the fin pocket is a good one to watch out for. A good Kingfish can wrap you with float line. Around the neck happens and is no fun, fin wraps are common.

  • Deep hunting – A big kingy can drown you if you fight it to the surface. Release enough line with a constant drag that allows you to surface safely. A good Snapper or other fish could cause the same and requires the same technique. If your shaft or fish gets jammed do not try to release it unless you have plenty of time. Surface and get your buddy to safety you if it’s a deep recovery dive

  • Always treat your speargun as loaded and never point at another diver. Watch for ascending divers as you gun is often point down in the water. Another hazard is swimming blindly with your speargun in front of you.


Want to know more?


Feel free to drop any of the Committee a line, or if you want to know more about some of the Apnea items listed above, here are some Freediving Club contacts:


Freediving New Zealand


Auckland Freediving Club 


Lazy Seals Freediving Club Wellington 


Breathtakers Freediving Club Palmerston North 

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