When I first started geocaching a good friend of mine gave me a whistle on a rope with a little charm on it. I haven't been as good about wearing it as I should be but it is was a good gift. She said that if anything happened, like cachers got seperated, you came across some danger, or fell and hurt yourself, to start blowing on the whistle to get someone's attention. Luckily I haven't had to use it yet, but it's just a suggestion to cachers out there. And yes, I do realize a cell phone is your best bet, but that's just my low tech 2 cents worth.