Apple Watch Ultra Depth Gauge: Accuracy, Range, and EN 13319

Apple documents the built-in Depth app on Apple Watch Ultra as working to a maximum depth of 40 metres (130 feet), which is also the recreational scuba limit. Apple notes that if you go below that depth the screen turns yellow and some functions may stop working or work intermittently. On non-Ultra models that support the Depth app, the documented maximum is much shallower. Because these figures and behaviours can change between watchOS versions, confirm the current range in Apple's own documentation rather than relying on a third-party summary.

Apple states the depth sensor on Apple Watch Ultra is accurate to plus or minus 1 metre. Depth gauges work by measuring surrounding water pressure, so real-world readings can be influenced by factors such as water movement, temperature, and device state. An accuracy figure describes the sensor under Apple's test conditions; it is not a promise about every dive. Treat the number as useful context for a measuring instrument, and keep depth decisions with your primary instrument and training rather than a single reading on any wrist-worn device.

Apple says Apple Watch Ultra is certified to WR100 (a water-resistance rating) and to EN 13319, which it describes as an internationally recognised standard for dive accessories including depth gauges. In plain terms, the depth-gauge function has been tested against a recognised standard for that specific instrument. Certification to a depth-gauge standard is meaningful, but it is scoped to the depth-and-time measuring function - it is not a claim that the device is a full dive computer.

Apple is clear that the built-in Depth app is not a dive computer and does not provide decompression stop information, gas analysis, or other scuba functionality. DiveOne only ever works with the data that Apple Watch hardware, watchOS, and your granted permissions make available, and it uses that data for recreational logging, review, and UDDF export or JSON backup - never for decompression, gas, ascent, or permission-to-dive decisions. Always dive with a certified primary instrument and proper training.