Earlier today I wrote a piece about Apple Watch Ultra\u2019s new Scuba diving feature, and a lot of folks came out of the woodwork to tell me they wouldn\u2019t trust a \u2018dive toy\u2019 to keep them safe under water. I respect their opinion, but I figured I\u2019d share why I feel fully comfortable trusting Apple on my scuba-diving adventures. Because, obviously, you need to read a 1,800-word opinion piece where I nerd out about scuba diving. Let\u2019s gooooooo.<\/p>\n
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First things first; I\u2019m not here to convince people who don\u2019t trust Apple otherwise; Scuba diving isn\u2019t without risk, and you are responsible for your own safety. If you don\u2019t feel comfortable with the Apple Watch Ultra to keep track of your dive safety, then there\u2019s a really simple solution: Don\u2019t use it.<\/p>\n
I have no qualms about doing so, however, and I\u2019ll tell you why.<\/p>\n
A bit of nerdy dive theory<\/h2>\n
To understand why the Scuba thing is such a big deal on the Apple Watch Ultra, and why I have no qualms trusting it, I\u2019ll need to, just for a moment, nerd out about spending time underwater for a moment. If you are Scuba certified, all of this is old news, feel free to skip ahead.<\/p>\n
You may have heard of decompression sickness, or \u2018the bends\u2019. It\u2019s a nasty set of symptoms that can occur when you breathe compressed air at pressure. These days, it comes up most often in Scuba diving, but it was originally discovered when workers were working in caves. It can also happen when you travel in unpressurized aircraft, and it\u2019s something astronauts worry about as well.<\/p>\n
In a nutshell: the air we breathe has around 78% Nitrogen, 21% oxygen, and 1% \u2018other\u2019 in it. The oxygen can be a problem \u2013 if you breathe pure oxygen at just 6 meters \/ 20 feet or so under the ocean, it becomes toxic, and you can have a seizure. As you can imagine, that\u2019s bad news when you\u2019re underwater.<\/p>\n
However, recreational scuba divers don\u2019t dive with pure oxygen, but instead with compressed air, or oxygen-enriched air. Either way, there\u2019s typically between 78% and 65% Nitrogen in the air in Scuba tanks, and that\u2019s the gas that causes problems; as you breathe it, the gas dissolves in your blood, and much like a soda bottle under pressure. When the bottle is closed, there\u2019s no visible bubbles. Shake it and open it, and suddenly you have a fountain of sticky goo. Your blood is like that, when under pressure: Come up from depth too fast, and the bubbles in your blood could come out of solution, which can cause all sorts of nasty symptoms.<\/p>\n
This is my \u2018I haven\u2019t the foggiest idea\u2019 pose. You\u2019ll see that a lot if you\u2019re following me around on dives. Gear to pay attention to in this photo: I\u2019m wearing my Suunto D9 watch (I\u2019m wearing it with the watch face on the inside of my wrist, because it makes it easy to look at as I\u2019m ascending). You can also see the gauge cluster tucked into my cumberbund, which includes the 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:<\/strong> \/ Haje Kamps<\/p>\n<\/div>\n A dive computer is designed to ensure that you don\u2019t over-load your blood and tissues with Nitrogen, and that you surface slowly enough that bubbles don\u2019t form. In short: If you limit how long you breathe at pressure, and if you surface at a reasonable rate, diving is pretty safe.<\/p>\n If you really want to nerd out on bubbles in liquids, start at Boyle\u2013Mariotte\u2019s law, and go from there. #SCIENCE!<\/em><\/p>\n There\u2019s two aspects to a good dive computer: Instrumentation, logging, and algorithms. The instrumentation is simple: Dive computers have a lot of features, but the important one is a pressure gauge and a clock. The dive computer logs how long you are at certain depths, and keeps track of that with a certain resolution. Some dive computers record that every 10 seconds, some every 30, and some more or less often, but the key thing is that it keeps track of things, so you don\u2019t have to.<\/p>\n The \u2018so you don\u2019t have to\u2019 part is important. When you learn how to scuba dive, you\u2019ll learn how to use so-called \u2018dive tables\u2019. Basically, these were designed by the US Navy for its divers, to ensure that if you stayed, say, 20 minutes at 10 meters depth, you could calculate how long you can dive for your next dive. The problem is that dive tables assume that you keep detailed logs of how long you are at which depth, which you could do, but most divers do not. To be conservative, then, you need to dive a lot less. A lot of people pay good money to go on dive trips, and you don\u2019t pay all that money to sit on a dive boat waiting for the nitrogen to offgas, so a better solution is a dive computer.<\/p>\n People doubting Apple do so because they don\u2019t trust the Cupertino-based giant to do the above accurately; but that\u2019s where I think they are wrong. Apple watches are exceptional at logging things; steps, heart rates, activity; it\u2019s all being logged.<\/p>\n The final piece of the puzzle is the algorithms to calculate how much nitrogen is in your body. This is a little bit complex; some tissues take on and release nitrogen slower than others, and each body is different. If Apple had said that it had designed its own dive algorithms, I\u2019d be highly sceptical. That didn\u2019t happen, though; the company announced that it had partnered with Oceanic to develop an app to take care of that side of things.<\/p>\n Ugh I miss scuba diving. This photo was taken in a Cenote (a cavern system) in Tulum Image Credit:<\/strong> \/ Haje Kamps<\/p>\n<\/div>\n Oceanic is a well-known, well-respected brand in diving, and they have their own line of dive computers. The company is developing an app \u2014 remember how TomTom and Garmin had mapping apps in the early days of smartphones because they were better than Apple at mapping? It\u2019s like that. In today\u2019s Apple event, Oceanic mentioned that they use B\u00fchlmann\u2019s algorithms for nitrogen loading and unloading. You can argue whether or not that\u2019s the right algo to use; some divers prefer the RGBM algorithm,\u00a0 there\u2019s VVAL, and some dive tables are based on Haldane\u2019s work (although I haven\u2019t seen that one in the wild, ever, it appears to be more of a historical artifact).<\/p>\n Regardless, I trust Apple to make good hardware and log its measurements. I trust Oceanic to create software to keep divers safe. And I trust the algos they\u2019ve chosen to calculate the nitrogen loading.<\/p>\n The interesting point to make here is that Apple watches rarely fail. But even if they do \u2014 or if Oceanic\u2019s app glitches \u2014 I hope that they are taking the same approach as most dive computers, which is to fail-safe. For some dive computers, that means a display that just says \u2018malfunction\u2019. For others, they just turn the screen off. As a diver, that can be super scary, but that doesn\u2019t mean you\u2019re going to die.<\/p>\nWhy I trust Apple with my diving<\/h2>\n
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<\/p>\nDoes that mean you\u2019re trusting Apple with your life?<\/h2>\n
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