After we started Geocaching we heard about hunting benchmarks. Benchmark hunting uses a mixture of urban archaeology, instruction translation, GPSr navigation, and digital photography to seek and log benchmarks. This page describes the basics of Benchmark Hunting.


The equipment we use for Benchmark hunting is a little more varied than our Geocaching equipment. We still use a GPSr (primarily to verify the benchmark location), but we also use a tape measure (to measure distances from objects), a digital camera (to record the benchmark and benchmark area), a compass (to identify directions when taking pictures), a wire brush (to clean the benchmark), a small trowel (to dig for the benchmark), and long thing screw driver (to probe for the benchmark). Iím sure as we continue new pieces of equipment will be added to our pack.

Where are the Benchmarks?

We primarily use to identify the benchmarks we want to hunt. The site provides a lot of information about Benchmarking, like: how to get started, descriptions and location of benchmarks in the United States, forums, etc. We also use the National Geodetic Survey (NGS) Datasheet Page to get current information about the benchmarks we want to find. The next sections give you quick overview how to use the and NGS sites to find and log benchmarks.

Get a account

To actually get the coordinates for benchmarks you need to sign up for a free account. To create an account you need to click on the log in hyperlink located at the site. If you are just starting out you probably don't need to sign up for a Premium Membership until you decide you actually like Benchmark hunting and want the additional features the you get with a Premium Membership.

Get local benchmark information from

Once you get your account you'll probably want to see what kind of benchmarks are near where you live. After you log in you can look on their Home Page and under "Find a Benchmark..." you can enter your zip code. When you select Go you'll get a page something like this:

The "A" column indicates the status of the benchmark. A Benchmark reported missing indicates that the mark has been officially reported as missing in the NGS database, a Didn't find it indicates that someone from could not find the benchmark, a Benchmark found indicates that someone from has found the benchmark, and a Benchmark not logged indicates a benchmark that has not yet been searched for by someone at The "B" column identifies the Permanent Identifiers (PID) for the benchmark (the NGS database key for the benchmark), the "C" column shows you how far and what direction the benchmark is from your location. The "D" column identifies the benchmark designator (if the benchmark inscription, this would be what is inscribed on it). The "E" column identifies the type of benchmark, and the "F" column identifies the found/not found status.

How to read a benchmark page on

For your first benchmark you probably want to pick one that is near your location, is a survey disk, and has been found by someone from The benchmark KV6137 "SWIM AZ MK" meets all of these requirements. If you click on KV6137 you should see something like this:

"A" points to the PID, "B" is a link to a entry for this benchmark in the NGS database, "C" points to the coordinates you would enter into your GPSr (notice it uses a NAD 83 datum), "D" points to the link that you can use to log your find, "E" shows the log entries from users, "F" details the instructions to reach the benchmark, and "G" identifies the designator of the benchmark.

You need to select the datasheet (at "B") or look at "F" to obtain the instructions to the benchmark. You should not rely on the coordinates ("C") to be completely accurate (many benchmarks were placed before the GPS was deployed, so the coordinates are sometimes estimated).

Logging your find at

When you search for a benchmark you should record your results (found, not found or destroyed) at the web site. Here are some guidelines for the three categories:

  •  Found - your found the actual mark! Since there can be other benchmarks near your benchmark you should ensure the mark on the benchmark is the same as what's identified in "G". When you find a benchmark you should take a close-up picture of the mark and a picture of the surrounding area (to help others locate the mark in the future). Also include any notes that would update the instructions to the mark (like road name changes, distance changes, etc.).

  •  Not found - you couldn't find the mark, or you think it's missing/gone/buried/etc. Sometimes the directions to the mark are not clear, or the area has changed and the mark may be buried, covered, etc. When you make your log entry describe where you looked and take a picture of the area. The entry may help you or others who may return to the site to attempt to try to find the benchmark in the future.

  •  Destroyed - only use this designator if you have evidence the benchmark is destroyed (you found it in a concrete base pulled from the ground, or it was supposed to be in a tower or other structure that has been destroyed). Do not use this designation if you think it may just be buried under some dirt or a road. Take a picture of the removed mark, or the area where the structure used to be. It can also be helpful to include any news articles describing the destruction of the structure.

The NGS PID database

The current status of the benchmarks that are in can be found in the NGS PID database. If you use the link to the database and enter "KV6137" you'll get a page something like this:

"A" points to the benchmark designator, "B" identifies the coordinates of the benchmark, "C" identifies the status and history of the benchmark, and "D" details the instructions to get to the benchmark.

Logging your find with the NGS

In addition to logging your results at, you can also submit your findings in the NGS Mark Recovery page. Professional surveyors, engineers, planners, etc. use this database, so if you want to log your findings in this database please be sure to be as accurate/precise as possible. Also note that there is no need to make a new entry in the database unless the previous entry is more than a year old, or you found a previously "Not Recovered" benchmark, or you have evidence of a Destroyed benchmark. Here are some quick instructions for filling out the form:

For "A" you enter the PID from the NGS Datasheet ("A"), "B" is the condition of the mark (note the special attention for Destroyed), you can select GEOCAC for "C" - this will also be recorded in the NGS Datasheet (at "C"), if you enter your initials in "D" they will be recorded in the NGS Datasheet (at "C") , "E" is the date (note the format), "F" is you name and email address (note why they ask), "G" is any additional information you want to provide in the database, like the road name changed, the distance has changed, etc. - these comments will be entered in the NGS Datasheet (at "D"). After hitting Submit, and verifying your PID, you will be asked about satellite coverage:

Answer the question based on your observations. You can look at the the NGS Data Sheet for a suggestion about Satellite Observations from the last log entry. If you are not sure then select "Don't know".

Other resources on the Internet

See the Geocaching page for additional recourses.


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Last Modified: March 11, 2006 02:54:02 PM