@_Davidsmith @marcoarment The cell coverage was almost non-existent so I had the phone on flight mode the entire trip. During stops I mostly did not use my phone - no coverage - so the screen was off most of the time.
I did not own an Apple Watch at the time so to my knowledge I did not record any other types of data, e.g. accelerometer based, heart rate, etc.
My point is just that GPS reception in isolation uses very little power I think.