As a standalone product the Apple Watch is already a pretty good 'adventure' watch with useful apps like the map and compass and add-ons like Wikiloc or Trailgo.

I'd like to think the first design challenge is a proper 2-day battery that lasts maybe 40-hours between charges for overnight camping. The top-end Garmin devices have things like a transparent solar panel for the 'glass' covering letting it charge perpetually during the day; I wonder if Apple would ever implement such an innovation?