His Remains were found 7 years later | Three Disappearances that happened in National Parks

I go over three disappearances that happened in National parks

Here are a couple of websites that you can take a look at to make a decision. I highly recommend you do your own research as i don't have any experience with these devices.
GPS Devices:
https://www.shedreamsofalpine.com/blog/best-gps-for-hiking
https://www.thebrokebackpacker.com/best-satellite-phones-for-backpacking/
https://www.digitalcameraworld.com/buying-guides/best-satellite-phones
https://www.switchbacktravel.com/best-handheld-gps

Url Links:
https://www.ancient-origins.net/unexplained-phenomena/dale-stehling-0015253
https://www.nps.gov/orgs/1563/cold-cases.htm