Hi there, I'm planning to develop a simple underwater compass app for Apple Watch Ultra 2, intended for recreational scuba diving down to 40 meters. The app itself does not need depth or pressure measurements beyond 6 meters. Its primary function is compass navigation using heading data. During a dive, however, I would like the app to: remain frontmost and visible throughout the dive; use Water Lock; use an underwater-depth WKExtendedRuntimeSession; continue receiving compass heading updates; allow interaction through physical controls such as the Digital Crown and Action Button; remain operational below 6 meters, potentially down to 40 meters. I understand that the Shallow Depth and Pressure capability limits CMWaterSubmersionManager depth/pressure data to approximately 6 meters, while access to depth/pressure data down to 40 meters requires the full Submerged Depth and Pressure entitlement. My question is: If my app does not require depth/pressure measurements beyond 6 meters, is the full Submerged Depth and Pressure entitlement still required simply to keep the underwater extended runtime session, UI, compass heading updates, and physical-control interaction working below 6 meters? In other words, does the 6-meter entitlement limit apply only to depth/pressure data, or does it also limit the ability of an underwater compass app to remain operational during a scuba dive below 6 meters? Target hardware: Apple Watch Ultra 2. Thanks in advance!

Apple Watch Ultra 2, watchOS 27.0, Xcode 27. I use CLLocationManager.startUpdatingHeading(), headingFilter=1 and CLHeading.magneticHeading directly, with no offset or GPS course. During surfing, my app and Apple Compass both showed an apparent error of about 180 degrees. The iPhone was not nearby or connected. Later, outside water, readings returned to normal. An analog compass on the opposite arm differed by about 30 degrees initially, then agreed. All saved Int(headingAccuracy) values were 89; it still displays 89 while the heading is correct. Raw fractional values were not saved. Is this an expected or sentinel value on watchOS? What calibration and diagnostics are recommended for the intermittent reversal? The app also uses an underwater-depth extended runtime session; its errors have not been linked to the heading issue.