An instruction manual for a snorkel you say. Surely it's just a bit of plastic tube around 30cm-long, bent round to where a mouthpiece is fitted.
Faithless reader, I am disappointed in you. This is a snorkel from the land that has a technological answer to your every need - provided you have the dollars to pay for it.
Until now, the prevailing belief has been that the flow of air through the snorkel (a German word for tube) should occur with the least possible resistance, the manual continues. Kadence Technology turns snorkel science upside-down.
Envisioned by an American doctor, the technology of this snorkel deliberately places a calibrated resistance into its exhalation path. This means, in plain language, that its harder to breathe out of than normal.
Im not a doctor but Im informed (by the manufacturer) that this small amount of pressure improves oxygen delivery and CO2 removal from the bloodstream. So much for that machine used by HSE medical examiners to measure how much and how fast a diver can exhale. A reduced resting respiratory rate, an improvement in performance and safety and lower anxiety levels are all promised - but promises can be broken.
The Kapitol Reef Luxury Snorkel is much fatter than any other snorkel.
This is because a separate exhalation tube runs up the centre of the inhalation tube.
Looking at the diagrams of how this product is meant to work made me think more of urology than lung functions. An inhalation valve at the top of the tube opens on demand. Another valve at the lower end near the mouthpiece directs exhaled air back up the exhalation tube.
This exhalation valve opens when the exhalation pressure is greater than that of the surrounding sea water or air, allowing expired air up the tube and forcing water out of the bottom of it. There is never any danger of re-inhaling any expired CO2.
So what happens when you breathe in and duck-dive down During a head-down descent, the inhalation tube is closed off, and the increased pressure provided by the Kadence Regulator being slightly deeper than the users head and lungs is said to counter the discomfort of water pressure against the sinuses and ears.
What I can confirm is that this is the biggest snorkel I have ever come across, and from a range of colours available, I certainly wasnt going to be seen with a big pink one. I was concerned that I might not be able to clear it, because I would be unable to blow up through the inhalation tube, as one does with a conventional snorkel.
My pal George Brown tried it and said he nearly drowned. He told me that there was no way he could clear it.
My experience was entirely different. True, there was more resistance to breathing than with a conventional snorkel, probably akin to that of a regulator, but I found it eerily dry.
I never got any water into my mouth, no matter what I did. I tried duck-diving, and found that the snorkel cleared miraculously, even before I had surfaced. The valve had shut off, preventing any water entering the inhalation tube, and when I exhaled I had only to clear water from the exhalation tube via the lower valve, so there was no head of water to shift.
Ophalie Marie, a French dive-guide in Hurghada, tried it. She told me that although she thought it felt strange, it worked. She found it completely dry.
Cadence is all to do with rhythm, and my breathing rhythm was certainly not broken by any spluttering, though after a bit some water must have built up on the exhalation side, because it made a slightly disquieting gurgling sound.
This made me expect water to enter on the next inward breath. It didnt. This product certainly beats a snorkel with a ping-pong ball in the top, but whether it beats a conventional snorkel when you consider the price is something youll have to decide. Ill be taking mine on my next trip for use between dives.

Comparable snorkels to consider:
Cressi Dry, £27
Atomic SV2 Flex, £50
Oceanic Ultra Dry, £40

PRICE Around £64, plus import duties.
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