I was pulled up by plain clothes police in a park in London (England)....I was recovering a micro cache on a piece of string down a drain.....there were people in the park but they were a long distance away....these people were police though, and although i thought i was being discrete they thought i was suspicious. They came over and asked what i was up to and explained who they were, i told them what i was upto, luckily i had the cache page with me to help explain as they had never heard of geocaching before. They weren't too bothered, although they did ask me to disable the cache because of hightened security and they didn't want people fishing things out of drains. Good to see they are security aware .