Freediving can be an extremely safe sport if participants learn and follow safety guidance, including measures to lower the risks of DCS. You should always exercise care while freediving and remain within your competence for length and depth of dive, gradually increasing these as your skill and physical capacity grow.
You can get “the bends”, the informal term for decompression sickness, from freediving, although it isn’t as common as in scuba diving. Some people may naturally have a greater vulnerability to DCS than others. Diving very deeply, diving for long periods and taking multiple dives over a short period, are amongst the factors which can increase the risk of decompression sickness.
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Many people still think that only scuba divers are at risk of the bends, or decompression sickness (DCS), caused by nitrogen bubbles forming in the body on diving ascent. Time to think again! Even though freedivers are not inhaling compressed air or other gas mixtures which saturate the body with nitrogen, they could still develop DCS from a single lungful of ordinary air, especially during longer, deeper dives.
At what depth do you get the bends freediving?
There is no single absolute depth limit beyond which you will definitely develop the bends while freediving. Similarly, while DCS risk rises with depth, limiting yourself to shallower dives doesn’t confer 100% protection. Length of dive, physical characteristics and environmental factors may all have an influence on the chances of getting the bends.
Common advice is that whatever the depth of your freedive, you should spend at least three times your dive time in recovery on the surface between dives. For example, after a two minute dive, you should wait 6 minutes at the surface before undertaking another dive.
Can you get the bends in 30 feet of water?
You can get the bends in 30 feet (around 9.1 meters) of water. While the bends is less likely to be an issue while diving in shallower water, it is still possible.
Some people may have a greater predisposition to DCS than others due to innate, lifestyle or environmental factors and therefore may be at risk of triggering some degree of DCS even at 30 feet. Dehydration, cold and a high carbon dioxide level could all raise the risk of getting the bends.
Length of dive and number of dives are also significant risk factors for DCS as well as depth. Undertaking multiple shallow dives over a longer period without sufficient rest time at the surface, may lead to accumulating more dissolved nitrogen in the bloodstream than undertaking a single shallow dive.
No matter what the depth of dive, spearfishers, recreational freedivers and competitive divers should all take care to limit the duration of their dives, rest sufficiently between dives and stay warm in the water.
If you’re thinking of diving at a 30 feet depth, we’ve written a whole article on freediving at 30 feet (opens new tab) which you should find useful.
Can freedivers get decompression sickness?
Decompression sickness is another name for the bends, a condition affecting divers which can cause pain, serious injury, or even death. While causal links between freediving and DCS are still the subject of research, there is significant evidence connecting them. The US National Institute of Health (NIH) has recorded over 90 cases of freediving-linked decompression sickness.
The air that we breath is made up of 78% nitrogen, 21% oxygen, and 1% other gases. Both oxygen and some nitrogen dissolve in the blood under normal pressures at sea level. When someone freedives, the massive pressure of the water on their body including the lungs, causes higher levels of both nitrogen and oxygen to dissolve into the bloodstream as they descend.
Oxygen in the bloodstream will be gradually consumed by the body during a freedive, but the nitrogen remains there. If they ascend slowly, this should allow nitrogen to dissolve gradually and safely out of the blood and body tissue. Ascending fast reduces pressure on the body too quickly and allows nitrogen gas to dissolve out from the bloodstream and be released as bubbles.
These nitrogen bubbles can cause painful blockage of blood vessels in limbs, rupture lung blood vessels, or trigger a heart attack or stroke.
Getting on an airplane shortly after diving, while dissolved blood nitrogen levels might still be higher than normal, could also trigger or worsen DCS. Ascending quickly to a great height, with commensurately lower air pressure, has similar effects as ascending too quickly in water. After scuba diving or freediving, you should allow a waiting period before getting on a plane to allow excess nitrogen to leave the blood.
How deep can you freedive without decompression?
We know that the deeper you dive, the greater the pressure exerted on the body by water, the more nitrogen may dissolve in the bloodstream, and the greater the risk of getting DCS. However, it’s difficult to give an exact figure for how deep you can dive before needing to make decompression stops on ascent.
Decompression stops are one way in which scuba divers mitigate the risk of DCS during their ascent. The term means pausing for a short period at each stage return to the surface, in order to allow the body to adjust and nitrogen levels in the blood to reduce.
During shallower freedives, decompression stops are not necessary. When diving moderately deeply, it’s better for freedivers to ascend slowly rather than stop completely. On very deep freedives (e.g. during elite “no limits” freediving competitions), decompression stops are very definitely necessary, and you should plan carefully these with your diving buddy or support team according to depth and your own previous experience and competence.
The deepest freedive on official record was a “no limits” freedive by Herbert Nitsch which reached a depth of 253 m (830 ft) in 2012. Nitsch developed DCS after this extremely deep dive, even while trying to make decompression stops.
How slow do you have to ascend to avoid the bends?
Freedivers should ascend at a moderate speed of 1m/s (3ft/s) or less, slowing down further during the last 10 meters. This should give nitrogen dissolved in your blood sufficient time to dissolve out without forming dangerous bubbles.
How to avoid the bends freediving
There are a number of measures you can take to help avoid developing the bends while freediving. These include:
- ascending from deep dives at a moderate pace (with decompression stops taken for “no limits” elite dives or similar),
- spending sufficient time at the surface after diving to allow your body’s blood nitrogen levels to return to normal,
- limiting multiple deep dives in a single session,
- limiting the length of a diving session even with shallower dives,
- staying warm and hydrated,
- ensuring there is no alcohol or other intoxicants in your blood when freediving,
- avoiding mixing freediving with scuba diving or airplane travel on the same day.