Looking for something to do with that GPS electronic navigation unit you received for Christmas?

You should take treasure hunting at the Michigan Geocaching Winter Convergence.

In geocaching, the hunters get the latitude and longitude of hidden caches on the Internet at www.geocaching.com, then use a GPS to try to find the caches in the real world.

The game began about four years ago, and now there are 80,000 caches in 195 countries.

Caches are usually ammunition boxes or Tupperware containers filled with trinkets like plastic toys, key rings and other inexpensive items.

Some contain disposable cameras the finders use to take pictures of themselves, and the person who runs the cache later posts those pictures on the geocaching Web site.

The finders take one of the trinkets from the cache, replace it with one they brought and sign the cache’s logbook. They can then log their find on the Web site and get credit for it. (Some geocachers have logged thousands of caches all over the world.)

The Internet description of each cache lists a degree of difficulty for the terrain it is in and how hard it is to spot. Most are relatively easy, with hints to locate the spot where they are hidden under a log or in the crotch of a tree.

But some are tough. My grandchildren and I once wandered around for 30 minutes before we found it — a tiny plastic film container that hung from a tree branch by a piece of 10-pound monofilament fishing line.

Some caches contain numbered plastic tags called travel bugs that the finders move from cache to cache, and people who find travel bugs can track their movements online.

One travel bug that was initially placed in Michigan had reached Australia a few months later.