Yesterday's Island Today's Nantucket
Volume 38 Issue 7 • June 12 - 18, 2008
now in our 38th season

Geocaching Nantucket Style

by Dr. Sarah D. Oktay
Managing Director UMass Boston Nantucket Field Station

Last weekend, on an unseasonably warm June day at the Nantucket Field Station, I participated in the kick-off event for the Nantucket Family Adventure Program which is sponsored by conservation and educational groups on island to encourage families to get out and enjoy nature while learning about our environment and habitats (more at  My job was to introduce families to the hobby/sport/game of geocaching by showing their kids how use a handheld GPSr (Global Positioning Satellite receiver) to find a geocache here at the Field Station.  Global positioning satellites are used in all forms of navigation today.  The receivers receive information from navigational satellites that allows the units to triangulate your position on the planet.  You can find them in rental cars, installed on many new cars, and in handheld devices from cell phones to Blackberrys.

Geocaching is a high-tech treasure hunt.  Someone hides a container of inexpensive trinkets in a waterproof container with a log book and then goes to a web sites accessed by geocachers to create the cache page, which makes the cache “live.”  They post the cache location using its exact latitude and longitude, and other people go hunting for it.  If the seekers find the cache, they trade items and sign a log to verify their successful find.  You should also sign the log online to note if you found it, as well as what you took from and put into the cache.  Lots of people post pictures and write very entertaining logs documenting their hikes, bug bites, up-close-and-personal interactions with poison ivy, or long search for the cache, which often is in a laughably easy hiding place.  Containers may be tiny waterproof match holders, magnetic key hiders, Tupperware, ammo boxes, or film canisters.

To get started, you need to get a GPSr.  Units run from $100 to $200.  On Ebay you can get decent used units for $15 to $75.  The two main companies that make them are Garmin and Magellan.  I have been using a Magellan SporTrak Pro since I first started geocaching 5 years ago, and I have been really happy with it. 

Next, you need to find some caches.  The people who place a cache log its location (latitude and longitude) on a web site.  There are several websites that support this game, but by far, the most extensive and most popular is — also called “Groundspeak.”  You get cache locations there and then return there to record your success or failure.  On the upper right of the main page, you can enter your zip code and get a list of the caches near you.  Currently, there are 18 geocaches on Nantucket scattered from Coatue to Lily Pond to Altar Rock.  No matter where you might live in the U.S. or around the world, there is a good chance that at least five to ten geocaches are within a five-mile radius of your home.  Most geocachers place caches relatively close to where they live so they can maintain them, and they are often placed in beautiful locations off the beaten path.  Part of the fun is finding these hidden gems in your state or neighborhood and enjoying the adventure of finding a cache.  Kids not only love to geocache, but they are experts at spotting a well-hidden Tupperware container—it’s a great way to get some exercise while enjoying some time with your family.

From the Geocacher Guide ( we learn that the genesis for geocaching was based on both treasure hunting and letterboxing.  Treasure hunting has been around for hundreds of years.  Participants would receive lists of items that they needed to procure and whoever would return first with the items on the list won.  In the mid-1800s, people began to do letterboxing, which is a form of treasure hunt that required deciphering clues left in landmarks and printed materials. Letterboxing is still a very popular game and several letterboxes are located on Nantucket. You can find them by going to  A letterbox is a British term for mailbox.  Letterboxing involves reading clues online, finding the box which usually includes a log book and an ink pad and stamp, and stamping your log book and the book in the letterbox.  Part of the fun is in making your own rubber stamp.

Geocaching first came about in the year 2000, when selective availability (SA) was removed from civilian GPS units.  Selective availability (SA) was originally designed as a way to constantly force a margin of error on non-military GPS units, so as to allow only the military a means of accurate GPS readings.  This was permanently removed on May 1, 2000. The only way to correct a GPS reading before that time was to use differential GPS, which uses fixed locations such as buildings to provide that correction factor.  On May 3, 2000, an Oregon resident planted the first geocache.  He posted the location on a Usenet group, and it was found twice within three days.  Since that time, thousands of people around the globe have found themselves obsessed with this game. The game was first known by names such as gps stashing or geostashing, but many early enthusiast felt that the term “stash” had too many negative connotations so they changed it to “geocache,” which more accurately describes the final goal, to recover a “cache” or concealed valuable or provisions derived from the French word “cacher” which means “to hide.”

So now you are ready to go find your first cache.  First let’s talk about some tips and tricks of the trade.  When you go to and decide which cache you’d like to find, you see a cache page that lists the latitude and longitude and a map of the location, the size of the cache, if there is anything special hidden in the cache, and the cache rating, which is two numbers between 1 and 5.  The first number indicates the difficulty in finding the cache, the second one is the terrain getting to the cache.  So a 1/2 (which is what I have at the field station) means that the cache is easy to find and the terrain is relatively easy to traverse (a 1/1 would mean you could get to the cache by simply driving or staying on a paved road or a very flat dirt road or trail).  A 1/5 could be an easy to see container that requires scuba gear to retrieve. There are a few difficult ones on Nantucket that involve using a boat or driving on the beach.  A 4/1 may be a very well camouflaged micro- or mini-cache in a state park near a trail.  I did one recently in Connecticut that involved climbing a 25-foot tree.

Next you need to know what you should or should not trade once you find the cache.  The rule is to trade even or trade up, don’t leave a penny and take a cool compass.  Small toys, interesting coins, souvenirs, personalized buttons, decks of cards, all make good cache items.  Never leave something smelly or a food item—animals will find these caches easier than we do.  You also need to keep an eye out for “muggles” in some areas, especially in downtown Nantucket.  Anyone who has read Harry Potter has heard of this term, but did you know that the term “muggle” is derived from the Classical Latin mugil ‘fish or fish tail’ and it has been around in many forms since the 13th century.  Back to our 21st-century muggles… in our geocaching world, this is a term used to describe a non-geocacher who may be watching when you are trying to locate a cache. When possible, most geocachers try to be a bit stealthy about their finds for two reasons: to not give away the location to nearby geocachers, and to avoid giving away the location to a muggle who may feel a need to vandalize or steal a cache.

To avoid mistaken identities, all official geocaches are well-marked with the name of the cache and should carry a document inside describing geocaching. Of course, in the post September 11th age, you would never want to hide (or look for) a geocache in an area that would arouse the suspicion of security officials.  If you place a cache, you should make sure you have permission to use the land where the cache is placed and that it is in a relatively safe area.

Last but not least, when you are hunting a geocache, trust your GPSr, but don’t be a slave to it.  It will get you within about 10 feet of the cache, depending on tree coverage and other satellite obstructions nearby.  After that it is up to you to use your eyes and clues on the cache page to find it.  A nifty addition to geocache pages is an encoded clue you can bring with you and decode if you need it.  Once you have purchased a GPSr, this is a very inexpensive hobby, requiring only a few trinkets, some water, good hiking boots, and a sense of adventure.  Geocachers often set up “cache in, trash out” (CITO) events where the location of a large BBQ or party is listed on the main site. Hundreds of families may show up to these events, which is a great way to meet fellow geocachers.  People who visit the Nantucket Field Station geocache come from all over Nantucket and all over the world.  I’ve found (or attempted to find) about 70 geocaches, and when I travel, the first thing I do is print up cache pages for the place I am visiting.  I hope to see you out visiting our ponds and natural spaces and enjoying this fun activity with your family.

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