Jeff, it is called geocaching.com. I think the app was $10, but it is more interactive than the handheld. You can get pics of the surroundings, times the cache has been found, if it has trackables in it and so on. It will allow you to follow a compass display to the cache or a map showing you and the destination. It will get you within 20-30 feet of the cache which is better than the handheld.
My son and I just got back from the Windy City a couple weeks ago on a school field trip and we were amazed at the number of Geocaches! Wish we had time to explore but the trip agenda didn't allow for it. I wish I would have checked for nearby caches at Wrigley when we were there for the Cubs game ( Cubbies lost
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Tracy