Marking this one as solved, but please do let me know if you foresee any issues with using the "airborne" activity type on a boat! The only obvious one I can think of is higher power consumption, but that's a worthwhile tradeoff for safety in this case.

Thanks for the heads-up on that value! I gave it a quick test and just setting that to false with the non-airborne activity types still results in paused lat/long for me. I keep getting location updates, but the updates contain the exact same lat/long even though I'm slowly moving. That said, I'll be sure to set it to false to make sure I keep getting the updates, too.

Did some more testing and re-deployed the app a couple of times. I think I just wasn't seeing the splash/startup because another app was keeping CoreLocation active, allowing my app to start up faster than expected. I could've sworn I saw it's background activity carry over after I swiped up, but sometimes a triple-check is all that's needed to clear up a mystery. Thanks!

Just tested on two different iPads (one older and one newer) with the airborne activity type and default "true" value for pausesLocationUpdatesAutomatically. While the older iPad updated coordinates regularly, I needed to set pausesLocationUpdatesAutomatically to false in addition to the airborne activity type to get consistently updating coordinates, so not all devices are created equal here, and adjusting both values is required, thanks again!