As far as GPS units go, our botanists use latitude and longitude to record
precise locations (i.e., within 10 or so meters accuracy) as well as
altitude.
 
With regard to use in the mountains, we have not had trouble thus far.
But, I don't know if anyone has attempted use while inside a steep
ravine...this may affect the ability to get readings but I think that the
manufacturer could address this point.
 
Our most interesting use to date is getting location readings from an
airplane while over flying a remote region--our botanists were doing some
"gross identifications" of plant communities worth hiking to at a later
date.
 
Richard Chute                           [log in to unmask]
 
Rancho Santa Ana Botanic Garden         Claremont, CA 91711
Phone:  (909) 625-8767, ext. 222
FAX:  (909) 626-6760