Apple Watch Ultra comes with a stock Depth app for underwater recreational activities like snorkeling and underwater pool swims, but most casual users probably won't get to see how the Depth app responds during the more committed activity of open water free-diving.
For anyone curious, tech reviewer and YouTuber DC Rainmaker has posted a video in which he demonstrates the Depth app in action at deeper levels, using an underwater test chamber designed for diving equipment.
With the help of a computerized depth simulator, DC shows how the Depth app fluidly responds to greater water pressure as a diver descends, showing the Meters and Feet readouts accurately adjust on the display as the background water animation fluctuates in kind.
The Depth app is designed for underwater activities at a maximum depth of 130 feet (40 meters), but Apple Watch Ultra has a water-resistance rating of 100 meters (328 feet), making the watch capable of withstanding greater depth pressures than the Depth app is designed for.
With this in mind, DC's test shows what happens in the Depth app when a diver descends below 130 feet: The screen turns bright yellow and reads "Beyond 130 FT," and no longer provides a depth reading until the diver returns to shallower water.
The test also demonstrates the Dive app's consolidated dive summary at the end of a dive session, letting users know the length of the dive, the water temperature range, and maximum depth. This data can be later found in the iOS Health app.
Apple warns that the Depth app is not a dive computer and it cannot provide decompression stop information or gas analysis. In situations where failure of the Apple Watch Ultra could lead to death or personal injury, Apple suggests using a secondary depth gauge and timer.
For deeper ocean water diving, Apple has partnered with third-party outfit Huish Outdoors to develop Oceanic+, a Dive computer specifically designed for Apple Watch Ultra models. As a free app on the App Store, Oceanic+ will include depth tracking (including depth alarms), GPS tracking, logbook (up to 12 dives), snorkeling, and more.
For more advanced diving options such as No Decompression Limit, users will be required to purchase an Oceanic+ subscription plan ($4.99/day, $9.99/month, or $79/year). Oceanic+ will be available on the App Store later this fall.
(Thanks, Sonny!)