A bomb squad detonated a suspicious device found in a tree at the University of North Dakota Sunday.
The device, which was a plastic pipe with caps on both ends and painted black, turned out not to be a dangerous item – but actually a geocaching drop,
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Similar incidents have played out dozens of times around the globe as geocaching becomes increasingly popular.
So what is geocaching? It's an outdoor adventure game where people use location-tracking maps on smartphones or GPS devices to find treasures hidden in innocuous containers across the globe.
There are 1,045 geocaches hidden in public places near Minneapolis alone, and more than 2 million worldwide, Geocaching.com says, with more than 6 million people playing the game globally.
'Suspicious' devices, persons
But the game is becoming a problem for law enforcement officials around the world, the Wall Street Journal reported. People hunting for the cache have been the subject of suspicious person calls to police, and the geocache containers have prompted investigations from bomb squads, the publication notes.
There are numerous news stories and posts on Geocaching.com about incidents of police being called in to investigate a suspicious device after someone who isn't familiar with the treasure-hunting game spots the geocache.
There is no regulation size or type of container for a geocache, the International Business Times reported. So in many cases, police have to send in a bomb-investigating robot to detonate the device – that's what happened on UND's campus over the weekend.
"It could easily be thought of as a pipe bomb," UND Police Sgt. Danny Weigel said, according to Forum News Service.
Because of similar incidents, police around the country have asked geocachers to use some common sense when they hide the containers, like avoiding placing them in urban spaces or high-traffic areas, the International Business Times notes.
Some players even inform police about where geocaches are hidden and provide a photo of the cache to avoid any confusion down the road, or mark the object with an official geocache label (pictured above).
Here's a look at some of the geocache containers around the world in honor of International Earth Cache Day on Sunday: