I Went Scuba Diving With the Apple Watch Ultra. Here's How It Works

The $799 (£849, AU$1,299) Apple Watch Ultra was made with adventurous types in mind. Its rugged construction and extended battery life will appeal to trail runners, marathon runners and mountain climbers. Since the Ultra is Apple's first foray into dive tech, the Cupertino-based company partnered with Huish Outdoors on the $10-a-month Oceanic Plus app. 

The app aims to make the Apple Watch Ultra your ultimate dive companion and compete with standalone dive computers, which are a key tool for any diver. Dive computers measure depth, duration-at-depth and make calculations to help divers stay safe from the dangers of decompression sickness.

I tested a prerelease version of the Oceanic Plus app with three dives off Catalina, California. I'm a relatively green diver and stayed well within my own limits, and those of the Apple Watch Ultra. I used the Ultra and Oceanic Plus app for predive planning, tracking my actual dive and the post-dive data summaries. My take: There are a lot of advantages to using the Ultra as a dive computer, but a few things about it aren't so good and others are just plain quirky.

The full version of Oceanic Plus is now available for download in Apple's App Store. Snorkel mode is free and the scuba features can be unlocked for $80 a year, $10 a month or $5 a day.

Apple Watch Ultra $591 at Amazon

Apple Watch Ultra: Predive planning 

You can plan a dive with the Oceanic Plus app from either the Apple Watch Ultra or your iPhone. The watch offers a No Deco Dive Planner, which calculates how long you can stay at various depths without a decompression stop. You simply enter your air mix and time until your next dive.

The iPhone app also offers a location planner where you can enter the dive site, or drop a pin, to get weather, water temperature and tidal information up to three days in advance.

In the Oceanic Plus app dive settings, you can add alarms for dive time, target depth, low No Deco time, and minimum temperature. You can also add various shortcuts, called complications, to the watch face itself. These take you directly to various parts of the Oceanic Plus dive app.

To compliment the Ultra and Oceanic Plus app, Apple made an elastomer watch band specifically for water-sports called the Ocean Band. It's well-engineered, secure, comfortable and fits well over a wetsuit or gloves. However, if you set up the Ultra with a passcode like I did, the sensor on the back might not detect your wrist through the wetsuit or gloves, prompting you to unlock the watch anytime you need to do anything. This wasn't a huge problem since the Oceanic Plus and Depth App can be set to launch automatically, but it did become inconvenient in one particular situation, which I'll explain later.

What it's like to dive with Apple Watch Ultra

Before my dive, I set the Ultra to automatically launch scuba mode on the Oceanic Plus app when submerged. Scuba mode displays your depth and No Deco Time at the top of the screen, except in the case of warnings and alarms, which briefly cover that information when they first pop up. Sometimes, the dive session started automatically when submerged, but other times I was prompted to press the orange action button on the side of the watch to confirm that I was "fit and ready to dive" before starting.

The Ultra has the biggest screen in the Apple Watch lineup, but compared to other dive computers it's quite small. This might be why the dive information is spread across multiple screens:

• First screen: dive time, minutes to the surface and water temperature
• Second screen: max depth, ascent speed and battery level
• Third screen: compass
• Fourth screen: air information, conservatism, gas mix and other parameters set during predive planning

Scrolling through the various screens with the digital crown was doable in gloves, but I accidentally scrolled past the screen I wanted a few times. I wish I could use the Apple Watch Ultra's physical side buttons to "press and hold" and toggle through the different dive screens.

The 360-degree style compass is intuitive to use. You set a heading by pressing the action button. Blue arrows on either side of the compass show how far off you are from that heading. Some dive computers can't display both a compass and depth information at the same time, so having both visible was convenient. The watch's depth data appeared to be accurate compared to other depth-measuring devices.

I set a target depth for some of the dives, and was able to feel the notification buzz through my gloves. The yellow notifications for Target Depth and Safety Stop take up most of the screen when they first pop up, but reduce in size after a few seconds. At one point, during a safety stop warning I noticed that when I moved my hand down below 19 feet, the safety stop countdown automatically turned itself off because I was too deep. When I raised it back up to 19 feet, it turned on again, keeping track of how much time had elapsed before turning off. Other dive computers simply prompt you that you're too deep for your safety stop and need to ascend.

There are also warnings for minimum temperature and to slow your ascent. As you ascend, the onscreen depth gauge gets increasingly red as you approach the excessive ascent rate limit. I triggered it once by accident and felt the Ultra buzz. But by the time I stopped ascending to check the watch, the warning was gone.

The beta version of the Oceanic Plus app I was using automatically provided post-dive data immediately after surfacing, which is a nice idea in theory. On my second dive, however, I must have triggered the post-dive data summary before actually descending, perhaps when I let the air out of my buoyancy control device to descend. At depth, I realized the watch wasn't in scuba mode and showed a post-dive summary instead. 

Because the Ultra's water lock disables the touchscreen, I had to surface, undo the water lock, and then use the touchscreen to launch scuba mode manually. Since the watch didn't register as being on my wrist due to my gloves, I had to enter a passcode to unlock the touchscreen with wet gloves which miraculously worked. I wouldn't want to have to try that in choppier waters.

Anytime the device is submerged, it's calculating depth and decompression.  Pressing the action button when submerged should automatically launch back into the app and continue the dive.

Early videos by Oceanic show a five minute timer activating before the dive officially ends, however this feature was not included in testing or the released version of the app.

On my third and final dive of the day, I compared the Oceanic Plus app to a wrist-worn dive computer as well as the dive computer built into my regulator. You can see below how the same information is displayed in different ways across devices.

The Apple Watch Ultra shows plenty of post-dive details

Divers log dives to track their experience, and the Oceanic Plus app makes this easy by creating post-dive summaries with all the information you could want. As with the dive planning, the post-dive information on the watch is simpler than the detailed version in the iPhone app. The watch shows a depth graph and your basic stats. The iPhone app has graphs for depth, temperature, ascent speeds and No Deco time. You can leave detailed notes in the iPhone app about visibility, surface conditions, current, gear used, dive buddies and more.

My logbook included extra false or accidental dives due to my aforementioned "dive summary" debacle, which were easy to delete after the fact. The Oceanic Plus app also calculates your no-fly time, because flying at high altitudes after scuba diving can cause decompression sickness just like ascending too fast can.

The Apple Watch Ultra and its titanium casing held up well after a day in the ocean, even though it got bumped up against the rest of my scuba gear. After 15 hours and three dives, the battery was still half full.

Apple Watch Ultra snorkeling mode vs. the Depth app

The Oceanic Plus app also has a free snorkeling mode which I tested alongside the built-in Depth app at my apartment complex pool. Snorkeling mode displays max depth, the snorkeling session duration, length of last dive, number of dives and water temperature. The built-in Depth app displays depth, dive time and water temperature, which can also be found in the Health app following your dive. You can access snorkel mode data in the Oceanic Plus' logbook, which also saves your snorkel or scuba location.

The free snorkel mode is a nice way to track dives and get a glimpse of how the Oceanic Plus app works, but it doesn't offer a whole lot more than the Apple Watch Ultra's built-in Depth app. The star of the Oceanic Plus app is clearly its scuba features.

Can the Apple Watch Ultra replace a dive computer?

It's clear that the Apple Watch Ultra and Oceanic Plus app are designed to be used alongside backup devices. This is likely part liability management and part common sense. Experienced divers will tell you that backups are always important to have when diving.

During my mostly shallow dives, the Ultra definitely felt like a smartwatch, which sometimes made it difficult to use as a dive computer. For example, most other dive computers don't have a touchscreen or a water lock, and they don't require a passcode. 

To help avoid these issues, it's best to have auto-launch enabled and the action button programmed to launch the Oceanic+ app.

I'd be interested to see if and how Apple and Huish Outdoors address shortcomings in future updates to the Oceanic Plus app. I'd also like to see if other dive computer tools could be added to the Oceanic Plus app. I'd be particularly interested in seeing wireless air integration, which tells you how much air you have left, since Huish Outdoors already makes dive computers with that feature.

Thanks to my dive support team: Eryn Brydon, Keline Kanoui, BlueHolic Scuba and the crew of the Sundiver Express. Without them, this day of diving would not have been possible.

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Correction, Dec. 6: This story initially highlighted a post-dive screen featured in early Oceanic Plus promo videos that is not featured in testing or the released app.