With warmer weather last weekend, Afton State Park was full of people looking to fit in some outdoor activity. And for those who want to do something a little more engaging than simply walking the trails, the park offers geocaching.

Geocaching is what Linda Radimecky, area interpretive naturalist with the Minnesota Department of Natural Resources, calls a "high-tech treasure hunt." Geocachers use GPS devices to track the location of a hidden container, which typically contains a logbook and several knick-knacks left behind by others who have already found the cache.

The state park system started its own geocaching program in 2008. The purpose, Radimecky said, was to attract new users to the state parks. While older visitors are often content to just take a walk through the park, younger visitors tend to want something more involved, she explained. Geocaching does that, while also incorporating technology into the natural experience.

"Now they have a purpose," Radimecky said.

Plus, geocaching often leads people to places that are not only impressive to see, but also places that aren't so well known.

How it works

Geocaching uses satellite tracking and global location coordinates to guide geocachers to their prize with the help of a GPS unit. When geocachers get the coordinates of a cache, they input them into the GPS unit, which tells them which direction and how far they need to go.

Some caches are multi-stage, like the one at Afton State Park. The original coordinates don't go directly to the cache; rather, they lead to another location that has a clue to lead people on to the next stage. Afton's cache currently has three stages, with puzzles at the first two for geocachers to solve in order to work out the next set of coordinates.

"It's a neat way to explore an area," Radimecky said.

The cache itself can be all sorts of sizes and shapes. Afton State Park's is an old ammunition box. Inside is a book for geocachers to sign as well as any number of other items, or "swag." Besides any items the cache's owner puts in, those who find it may also leave a token of their own, or trade something of theirs for something another geocacher left behind.

At the state parks, the caches focus on an annual theme. This year's is "Call of the Wildflowers," and each park cache has a information card about a particular wildflower. Everyone who finds a state park cache is encouraged to take one of the cards.

There aren't many rules when it comes to geocaching, but there are some. First is that when a cache is found, it must be replaced in exactly the same spot so that future geocachers can find it. Second, if you take swag out of the cache, you need to put something back in. Lastly, cache locations should be kept as secret as possible, especially from "muggles," or non-geocachers. Radimecky said that geocachers are encouraged to be discreet when searching for a cache.

There are 75 caches in state parks and trails now, and the parks let visitors check out a GPS unit for free at the park entrances. It's a year-round activity, although some parks might require skis in the winter.

There are a number of smartphone apps available to geocachers as well, although Radimecky cautioned that cell phones might lose signal in low areas. Cell phones get their signal from towers built on the earth's surface, while GPS units communicate with satellites.

Geocaching goes beyond the state park system. There are about 2 million geocaches placed around the world. There are more than 300 caches within a 10 mile radius of Hastings alone. The caches are listed on www.geocaching.com, which is the go-to place for geocachers across the globe. Minnesota state park caches are listed there alongside many others. The site also has more information for anyone interested in geocaching.