As a diver, I would gladly trust my life to the Apple Watch. Here’s why.

Earlier today I wrote an article about the Apple Watch Ultra’s new diving feature and many people told me that they wouldn’t trust a ‘dive toy’ to protect them underwater. I respect their opinion, but I wanted to share why I feel completely comfortable trusting Apple with my diving adventures. Because, obviously, you need to read an 1,800-word op-ed in which I’m a scuba geek. Come.

In the first place; I’m not here to convince people who don’t trust Apple otherwise; Diving is not without risk and you are responsible for your own safety. If the Apple Watch Ultra doesn’t work for you to keep you safe while diving, there’s a very simple solution: don’t use it.

However, I have no reason for that, and I will tell you why.

A bit of geek diving theory

To understand why Scuba is so important on the Apple Watch Ultra, and why I have no qualms about trusting it, I’ll need to, just for a moment, consider spending time underwater for a moment. If you are a certified diver, this is all old news, feel free to skip.

You may have heard of decompression sickness or ‘the curves’. It is a set of unpleasant symptoms that can occur when you breathe compressed air under pressure. Today, it appears most often in diving, but it was originally discovered while workers were working in caves. This can also happen when traveling in an unpressurized aircraft, and it’s something astronauts worry about as well.

In short: the air we breathe contains about 78% nitrogen, 21% oxygen and 1% ‘others’. Oxygen can be a problem – if you breathe pure oxygen just 6 meters / 20 feet or more under the ocean, it becomes toxic and you can have a seizure. As you can imagine, this is bad news when you’re underwater.

However, recreational divers do not dive with pure oxygen, but with compressed air or oxygen-enriched air. In any case, usually between 78% and 65% nitrogen in the air in scuba tanks is the gas that causes problems; As you inhale, the gas dissolves in your blood, much like a pressurized soda bottle. When the bottle is closed, there are no visible bubbles. Shake it and suddenly you have a sticky fountain. This is what your blood is like when it’s under pressure: rise from the depths too quickly and the bubbles in your blood can come out of solution, which can cause all sorts of unpleasant symptoms.

This is my ‘no idea’ pose. You will see this often if you follow me on dives. Gear to look out for in this photo: I’m wearing my Suunto D9 watch (I wear it with the dial on the inside of my wrist, because it’s easier to see when I’m climbing). You can also see a set of gauges tucked into my cumberbund which includes a compass (visible) and on the other side an air pressure gauge to see how much air is left in my scuba tank and a depth gauge to see how deep I am. image credit: TechCrunch / Haje Kamps

A dive computer is designed to ensure that you don’t overload your blood and tissues with nitrogen and that you surface slowly enough to avoid bubbles. Bottom line: if you limit the time you breathe under pressure and if you surface at a reasonable speed, diving is quite safe.

If you really want to understand bubbles in liquids, start with the Boyle-Mariotte law and work your way up. #SCIENCE!

Why I trust Apple with my sauce

There are two aspects to a good dive computer: instrumentation, logging and algorithms. Instruments are simple: dive computers have many features, but the most important are the pressure gauge and the clock. The dive computer records how long you are at certain depths and monitors it in a certain resolution. Some dive computers record it every 10 seconds, some every 30 seconds, and some more or less often, but the main thing is that it keeps track of things so you don’t have to.

The “you don’t have to” part is important. When you learn to dive, you will learn to use what are called ‘dive charts’. Basically, they were designed by the US Navy for their divers, to make sure that if you stay, say, 20 minutes at a depth of 10 meters, you can calculate how long you can dive for the next dive. The problem is that dive tables assume you keep detailed records of how long you were at what depth, what you were able to do, but most divers don’t. To be conservative, you have to dive a lot less. Many people pay good money to go on dive trips, and you don’t pay all that money to sit on a dive boat waiting for the nitrogen to come out of the gas, so a dive computer is a better solution.

People who doubt Apple do so because they don’t believe the Cupertino giant will do the above correctly; but I think they are wrong here. Apple watches are exceptional at recording things; steps, heart rate, activity; everything is recorded.

The last piece of the puzzle is the algorithms to calculate the amount of nitrogen in your body. This is a bit complex; some tissues absorb and release nitrogen more slowly than others, and every body is different. If Apple said it designed its own dip algorithms, I’d be very skeptical. But that didn’t happen; the company has announced that it has partnered with Oceanica to develop an app to take care of that side of things.

Ugh, I miss diving. This photo was taken in a Cenote (cave system) in Tulum image credit: TechCrunch / Haje Kamps

Oceanic is a well-known and respected brand in diving, and they have their own line of dive computers. Company Develops App – Remember how TomTom and Garmin had mapping apps in the early smartphone days because they were better than Apple at mapping? And so. At today’s Apple event, Oceanic mentioned that they use Bühlmann algorithms for nitrogen filling and emptying. You can debate whether this is the right algorithm to use; some divers prefer the RGBM algorithm, there’s VVAL, and some dive tables are based on Haldane’s work (although I’ve never seen it in the wild, it seems to be more of a historical artifact).

Regardless, I trust Apple to make good hardware and record your measurements. I believe Oceanic will create diver safety software. And I trust the algorithms they chose to calculate the nitrogen load.

Does this mean you trust Apple with your life?

It is interesting to note that Apple watches rarely fail. But even if they do – or if the Oceanic app crashes – I hope they have the same fail-safe approach as most dive computers. For some dive computers this means a screen that just says ‘failure’. For others, they just turn off the screen. As a diver, this can be super scary, but it doesn’t mean you’re going to die.

I am personally a PADI Certified Dive Instructor and an SSI Certified Rescue Diver. That doesn’t make me infallible, but it does mean I can lead certified dives. In theory this also means I know what I’m talking about, but I’m 99% sure that diving geeks will be able to find a mistake or two in this article. Forgive me, and if you spot any mistakes, I don’t know. tweet me on a cell phone or something.

Would it be too bad to resort to a backup plan? It’s clear. But only because it ruins your day, not because it will kill you. Haje Kamps

In my role as a dive leader, I usually dive with two dive computers (Suunto D9 and Suunto Zoop if you’re curious). The first one looks like a wristwatch and can be worn regularly. The latter looks like a hockey puck. You can wear it around, but you look a little silly. In any case, this means that there is a reserve. The reason I do this is because, as a dive master, you have to look out for the people in your group. If my dive computer fails, that would mean I can no longer dive that day. That would be awful. So I’ll bring a spare. In hundreds of my dives, I have never had a dive computer fail – neither my primary nor backup.

If I were to dive with the Apple Watch Ultra as my primary dive computer, I’d probably have a spare stuck in my buoyancy compensator pocket (this is the vest-like thing that the dive tank is for). But even if I didn’t, if the Apple Watch somehow fails, that’s not, in and of itself, a truly fatal problem.

A huge amount of scuba training goes into practicing what to do if a piece of equipment fails. Safe surfacing is a key aspect of this. Without a dive computer, you’re swimming blind – but almost all diving devices have a depth gauge as part of their equipment. It means you know how deep you are. Even without that, you can safely reach the ‘next smallest bubble’ surface. In other words: exhale, look for the smallest air bubble you can find, and rise to the surface as slowly as that bubble. This is usually slow enough to prevent decompression sickness.


Diving training involves many skills, including underwater navigation. The less we say here about my friend Will and the 30 minutes of swimming we had on the boat, the better. image credit: TechCrunch / Haje Kamps

Another point here is that most recreational diving certifications include the assumption of a buddy system. This means that for your dives you dive with another diver who stays with you for most of the dive. You shouldn’t do this, of course, but if your dive computer fails, it’s not entirely unreasonable to believe that its computer is a relatively close mirror of your dive profile. Do it with a little more slowness and care and you’ll probably make it to the ship safely. And, of course, even if your dive buddy doesn’t have a working computer, your divemaster probably does, so he can act as a substitute for your nitrogen load if needed. You shouldn’t, it’s not advisable, and it doesn’t matter: what I’m saying is that you’ll probably get back on the ship safely.

Now, would it be too bad to have to resort to one of the backup plans? Of course it would be boring. But only because it ruins your day, not because it will kill you. At this point, you relied on your dive computer to protect you. Without it, you don’t know how much nitrogen is inside your body, which for a conservative diver means the end of the diving day. It sucks, especially if the failure happened on the first dive of five days of diving, but that doesn’t mean your life is in danger.

That’s why I trust Apple: it’s one of the best hardware manufacturers in the world. Implementing fairly basic instruments (time and pressure gauge) on the device will probably be fine. If I’m leading a dive, I’ll have a spare with me, but even if I’m not leading, I’ll have a dive buddy and dive leader with me. Even if I don’t have other equipment with me, the worst possible scenario is to miss a day of diving.

Now I just need to convince TechCrunch to let me hang out in Sipadan for a week and hang out with a bunch of tropical fish. I promise to give the Apple Watch Ultra an extremely thorough review.

Leave a Reply

Your email address will not be published. Required fields are marked *