Sorry to start with the somber stuff, but I wanted to leave you on a positive note. With a simple permanent marker, you now have the ability to write and make marks on virtually any dry surface. Did you get lost? A marker (plus a little survey tape) can indicate trails that you can use to prevent further wandering, and create weatherproof trails so that rescuers can better find you. Don't have the survey tape? Then write on surfaces on which the marker will show up, smooth rocks, bark-less logs, or whatever.