In 2023, a team of researchers had twenty healthy volunteers swim with two full-face snorkeling masks and a classic snorkel. At light effort, nearly one in two trials with a full-face mask had to be stopped because the inhaled CO2 exceeded the threshold set by the protocol.
This figure does not say which snorkel to buy. However, it reminds us that the tube you put in your mouth affects your breathing, and not just your comfort. We reviewed it with the European standard, two dated studies, and a simple rule: no product tests, no brand endorsements.
This article provides information and does not replace the advice of a qualified diving medicine doctor.
Simple snorkel, purge valve, or “dry”: what are the differences?
A simple snorkel is an open tube with a mouthpiece that you clear by blowing hard. The model with a purge valve adds a valve at the bottom of the tube, which expels water when you exhale. The “dry” snorkel closes its top opening when it goes underwater, and the “semi-dry,” in between, only has a deflector against waves.
Each added part solves one problem and creates another.
The purge valve helps beginners who still swallow water after each duck dive. But a membrane stuck by salt or blocked by a grain of sand lets water in at the wrong time. The “dry” system cuts off water entry when you descend. It also adds a float, some weight at the top of the tube, and an additional mechanism to rinse. The simple snorkel, on the other hand, has almost nothing that can fail.
The right choice therefore mainly depends on your usual sea conditions and what you do on the surface. For a snorkeling trip in calm water, with frequent breaks and little waves, a simple or purge snorkel is often enough, whereas regular chop makes the deflector or the “dry” more comfortable. Test it in a pool.
Which snorkel to choose for freediving?
In freediving, most practitioners choose a simple snorkel, often flexible, without a valve or “dry” system. It interferes less during the descent. It folds against the mask and traps no air bubbles. Since you don’t breathe through it at depth, a valve brings no benefit once the duck dive is done.
The flexible snorkel also fits more easily into a wetsuit pocket.
The only real criterion remains the shape of the mouthpiece. A mouthpiece that is too hard or poorly oriented tires the jaw during long surface recoveries, and that’s where you spend most of the session. However, many freedivers spit out the snorkel before descending. This gesture prevents inhaling, on the way back to the surface, the water that stayed in the tube during the entire descent. It is learned in a club, with a buddy watching you from the surface.
Choose it short and simple.
What does the EN 1972 standard say about length and volume?
The EN 1972 standard regulates snorkels sold in Europe. Its 2015 version distinguishes two classes: Class A for adults and Class B for children, with a size limit of 1.50 m mentioned in the instructions. DAN Europe reminds that the internal volume must not exceed 230 ml for an adult and 150 ml for a child.
| Reference | Adult (Class A) | Child (Class B) |
|---|---|---|
| User height | Over 1.50 m | Under 1.50 m |
| Maximum internal volume | 230 ml | 150 ml |
| Maximum length (indicative, instructions aligned with the 1997 version) | 38 cm | 35 cm |
Why limit the volume? Because the air remaining in the tube at the end of your exhalation goes back into your lungs on the next inhalation. This is dead space. A classic snorkel adds about 160 ml according to a series of cases published in 2025. The longer or wider the tube, the more you breathe back your own CO2.
The full table of the 2015 version is not freely accessible, so the lengths above come from manufacturer instructions that refer to the older 1997 version.
So, remember this above all. Never extend a snorkel. A child should use a Class B model, even if an adult snorkel “fits” on their mask.
Full-face snorkeling mask: what do the studies say?
Recent studies go in the same direction: the full-face mask increases inhaled CO2. In 2023, a study published in Diving and Hyperbaric Medicine stopped 45% of trials with a full-face mask at light effort, compared to 20% with a classic snorkel. In 2025, pediatricians described three serious accidents in children under six years old.
The mechanism lies in the pocket that covers the nose and mouth. If the air does not circulate in only one direction, part of your exhalation remains in the mask and returns to the next inhalation. The 2023 study estimates the dead space of this pocket at about 250 ml. It can rise to 1,470 ml depending on the model if the seals or valves malfunction. Volunteers also showed more episodes of oxygen deprivation.
And in children, the calculation becomes frankly worrying, since the 2025 case series recalls that a 20 kg child moves about 140 to 200 ml of air per breath, sometimes less than the dead space of the mask itself.
These accidents can be silent.
You will not be told that a specific model is safe or dangerous, because it has not been measured. The authors of 2023 cite several accidents, including deaths, associated with these masks. If you use one anyway, keep your efforts light and never let a young child swim alone with it. For a beginner, a classic mask and a snorkel meeting standards remain the best documented solution.
Should you keep a snorkel when scuba diving?
The debate exists and there is no single answer. The snorkel is useful on the surface, when you are waiting for the boat in choppy water or when you return with little air. At depth, it can get caught, interfere with the backup regulator, or flap against the mask. Your training and your club set the rule.
For: rough surface. A diver who has emptied their tank more than expected and must swim two hundred meters against the wind breathes better with a snorkel than by lifting their head at every wave. Against: the bottom. A snorkel attached to the mask rubs, catches the current, and sometimes gets stuck in a line. Many divers therefore keep a foldable snorkel in a pocket.
For a baptism dive or a first trip, it is impossible to decide from here.
However, the practical question arises before leaving: does your club require a snorkel on board, and on which side to wear it? The most common practice places it on the left, since the regulator comes on the right, but this detail is checked at the briefing and not in a guide. The cost of forgetting it remains modest: a few euros and a pocket of the jacket occupied.
How to maintain and when to replace your snorkel?
A snorkel should be rinsed with fresh water after each outing, including the valve, then dried in the shade, away from direct sunlight. Check the mouthpiece before each season: a crack, a bitten fin, or silicone that has become sticky are reasons to replace it. A deformed purge membrane lets water through.
Sand remains the main enemy of valves.
Before storing your equipment, run fresh water through the tube from the top, then from the mouthpiece. Gently press on the membrane to detach salt. Dry everything before closing the bag. A damp snorkel sealed for several weeks ends up smelling bad, and black stains inside the tube do not always come off. Store it away from the sun.
Yet, hygiene matters even more in rental, since a loaned mouthpiece passes from one mouth to another without you really knowing how or when it was disinfected. Taking your own snorkel solves the problem. Add diving booties suitable for beach entries and fins chosen according to your level, and you have a light kit.
The right snorkel according to your outing
For a snorkeling trip in calm water, a simple snorkel or one with a purge valve meeting standards is sufficient. For freediving, take a flexible model without a valve. In rough seas, the deflector or the “dry” snorkel provide comfort when waves fill the tube at every wave. For a child, class B is mandatory.
In short, the choice costs little.
Before a trip, also look at the spot conditions. A sheltered bay, like most snorkeling spots in France in summer, does not require the same equipment as an offshore outing. The best snorkeling destinations in the world mix both. The rental operator, finally, will not always tell you if their equipment meets the standard. Ask.
But the real expense hides elsewhere: a poorly adapted €20 snorkel will shorten each outing, whereas a standard-compliant and well-fitted model gives you an extra hour of comfort in the water.
FAQ
What length of snorkel should an adult choose?
The EN 1972 standard limits the internal volume to 230 ml for an adult. Instructions aligned with the previous version indicate a maximum length of 38 cm. A longer tube increases dead space and the CO2 you breathe back in.
Is the purge valve snorkel suitable for beginners?
It helps to clear water by blowing with less force, which often reassures beginners. Its membrane must remain clean, otherwise it lets water in. Rinse it after each outing.
Are full-face snorkeling masks dangerous?
A 2023 study shows that they increase the CO2 breathed compared to a classic snorkel, especially during exertion. A case series published in 2025 describes three serious accidents involving young children. The classic mask with a snorkel that meets standards remains the best documented solution.
Can the same snorkel be used for scuba diving and freediving?
Yes, a simple and flexible snorkel is suitable for both. In freediving, valves and “dry” systems are avoided. In scuba diving, your club sets the rule on wearing the snorkel.
Sources
- Full-face snorkel masks increase the incidence of hypoxaemia and hypercapnia during simulated snorkelling compared to conventional snorkels (Grundemann et al., Diving and Hyperbaric Medicine, 2023)
- Full-Face Snorkeling Masks Carry a Risk of Hypercapnia and Drowning in Younger Children: A Case Series (Trapani et al., Children, 2025)
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