Geocaching is an outdoor "treasure hunting" activity. Players use a Global Positioning System (GPS) (typically using a smartphone) to locate a hidden box (called a geocache, pronounced GEE-oh-cash) and discover the interesting things left inside by the creator as well as other players, and then sign the log book and read/write comments. The game is managed through a website, www.geocaching.com which players use to load new geocache locations into their device, leave reviews for the ones they have found, communicate with other players, and earn points for playing. The game is free to play, however you can choose to pay to access more features of the website. You absolutely do not have to pay to play, the additional features are really more designed for more advanced users who compete to be the first to find a new geocache, or want to find large numbers of geocaches efficiently to earn a high score.
Here is a picture of what's inside your typical large geocache (most are smaller than this one):
There are a surprising amount of geocaches present in the Santa Cruz area, with more and more being added as time goes on and the game grows in popularity. People have hidden these caches in places ranging from the middle of downtown, to deep in the forest.
For those who love to explore the outdoors (hikers, bikers, backpackers) geocaching can be a fun way to see new places and add an element of reward to an already enjoyable activity. Many people who play the game enjoy these activities, and you can usually find a geocache along most hiking trails.
Below is an image from the geocaching website, showing the geocaches available in the UCSC area (note: this image is from April 2015, the game is constantly changing and may look very different now):
Each box on the map is an individual geocahe. As can be seen, there are about 40 geocaches just in this area. Here is a link to this map: http://coord.info/map?ll=36.98576,-122.06188&z=14
Overall, geocaching is a fun activity that you can do solo or with a group. You can use the website to meet people who want to get out and play and explore nature!
One of my favorite geocaches that I've done in Santa Cruz was called "La Barranca Park". This was a special type of geocache which involved solving multiple puzzles before the final location of the box was revealed. While completing it, I got to learn a bit of Santa Cruz history (the puzzles used information in the signs along Bay street, so you had to pay attention) as well as see more of the city.
If you want to get started, and you want to play for free using your smartphone, go here: https://www.geocaching.com/mobile/