The depth sensor on the Apple Watch Ultra 2 is accurate to ±1 meter and can measure depths up to 40 meters (130 feet). The device is designed to automatically activate the Depth app when submerged to a depth of 1 meter (3 feet) or more. If the depth exceeds 40 meters, the screen will turn yellow, indicating that some functions may be impaired or stop working altogether[1][2][4].
While the depth sensor is compliant with the EN13319 standard, which is recognized for dive computers and gauges, it is important to note that the Depth app is not a substitute for a dive computer. It does not provide critical information such as decompression stops or gas analysis, which are essential for serious diving activities. Users are advised to use a secondary depth gauge and timer when engaging in recreational scuba diving[1][5].
Citations:[1] https://appleinsider.com/inside/apple-watch-ultra/tips/how-to-use-the-depth-app-on-apple-watch-ultra
[2] https://support.apple.com/en-la/102273
[3] https://discussions.apple.com/thread/255640553
[4] https://support.apple.com/guide/watch-ultra/measure-underwater-temperature-duration-depth-apd9073c83d6/watchos
[5] https://www.macrumors.com/how-to/apple-watch-ultra-use-depth-app/
[6] https://support.apple.com/en-md/118571
[7] https://www.apple.com/apple-watch-ultra-2/specs/
[8] https://support.apple.com/en-in/111832