Looking for a fun, family-friendly way to exercise both mind and body? Try geocaching, the fast-growing sport that’s akin to a modern-day treasure hunt, using the skills of problem and puzzle solving. Instead of a worn map marked with an X, you use a GPS receiver, a set of coordinates and (optionally) clues. And instead of hunting for a buried chest, you’re looking for a cache of goodies hidden in an eco-friendly site above ground.

Caches are hidden all over the world by fellow geocachers who put together a hodgepodge of trinkets, a logbook and pen or pencil, and perhaps a disposable camera. This hoard is then stuffed into a weatherproof box and hidden under a rock, behind a tree or maybe even in a more urban locale.

The geographical coordinates of these containers—some no bigger than a film canister—are posted on one of several Web sites for fellow geocachers to follow. One of the first and still most popular sites is geocaching.com. A list of caches in the Algarve can be found at http://www.geopt.org/index.php/tourism/geotourist-guided-tours/algarve