Frustrating. Even if the phone is "Off", Bluetooth is usually still active for at least another day or two, so any other iPhones in close proximity can usually pick up the Bluetooth signal and use that to help display the location on the Find My map. We assume that you had Find My enabled on the phone.
But, there probably aren't any other iPhones in the woods in close proximity to your phone.
It's a shot in the dark, but if you have some friends who have iPhones and you can retrace your general path in the woods, the other phones might be able to pick up the Bluetooth signal from your phone.
Now, if the battery on your phone has run down completely, things are not going to work unless you can spot the phone with a pair of eyes. A metal detector might help if you can bring one along.