Ye Ole Survey Monuments Series

Welcome to our Frequently Asked Questions (FAQ) section!

Here, we've compiled a list of commonly asked questions to provide you with quick and comprehensive answers. Whether you're seeking information about the Ye Ole Survey Monuments series, or general inquiries, this section is designed to help you find the answers you need efficiently.

If you don't find what you're looking for in our FAQ, please feel free to reach out to us through our contact form. We're here to assist you and ensure you have the information necessary to make your experience with us smooth and enjoyable.

Ye Ole Survey Monuments, commonly known as YOSM (GC45CC), made its mark in geocaching history when it was placed on 25 March 2002 by outforthehunt. This traveling virtual geocache added a unique dimension to the geocaching experience, leading seekers to specific survey monuments, pillars, surface blocks, rivets, or bolts scattered across the country.


The cache, as it journeyed through various locations, allowed multiple logs since each spot was a distinctive destination. However, this practice came to an end in 2017 when Groundspeak decided to archive the cache due to changes in guidelines. Despite its archival, YOSM had already etched its place in geocaching history with an impressive tally of 25,076 finds contributed by 3,528 different cachers.

A trig point, short for triangulation point, is a marker used in surveying to measure distances and angles across landscapes. Typically, it's a pillar or column with a triangular metal plate on top. Surveyors use trig points to create a network of triangles for accurate mapping. While GPS is now commonly used, trig points hold historical and symbolic value and are sometimes maintained as landmarks for recreational purposes.

Trig points come in various types, each serving specific surveying purposes. The common types include:

  1. Pillars: The classic trig point, a sturdy pillar made of concrete or metal.

  2. Berntsen Markers: Metal markers often set into the ground, used when a pillar is impractical.

  3. Surface Blocks: Concrete blocks flush with the ground, providing a stable surface for measurements.

  4. Towers: Tall structures or towers that serve as trig points, offering visibility over long distances.

  5. Intersected Stations: Points where survey lines intersect, marked for triangulation.

The choice of trig point type depends on the terrain, purpose, and practicality for surveying in a particular location.

It would be a time-consuming process to catch up on the old YSM stats, so we've decided that with a newly revived series also comes new stats. So, why not make this an excuse to visit those trig points again that you may have explored all those years ago?

To keep the legacy alive for the old YSM series, which was managed by OutForTheHunt, any locations that the previously virtual Ye Ole Survey Monument visited will retain their old numbering if a physical cache is placed. Any new trig points that weren't included in GC45CC before its archival will receive a new number.

Great, and we'd love to have you on board! All you need to do is find an accessible trig point, create a cache page, and then fill out our New Request Form to provide us with the details that we need to issue your Ye Ole Survey Monument number.

Obviously, it wouldnt be advisable to hide your cache on private land in this case. However in these instances we will adpot a line of sight guideline, as long as you can see the trig point from the physical cache location we will happly let your cache join the series. If your final cache hide is located at a distance from the trig point, I recommend incorporating a waypoint as a reference for your visitors. This will aid them in triangulating their position with the physical trig point.


It is your reponsibilty to advise your visitors of any rights of way issues. Remember to always follow geocaching guidelines and respect local regulations.

We encourage caches to be positioned as close to the trig point as possible, although we understand that this may not always be practical. We aim to avoid static puzzles that merely invite armchair solving, as we believe in promoting exploration and interaction with the trig point. Instead of traditional puzzles, we encourage cache owners to design dynamic and captivating experiences that inspire geocachers to actively visit and appreciate the trig point within its natural setting. In this way, the cache becomes an integral part of the broader adventure, elevating the overall geocaching experience.


As an illustration, consider the use of a Multi-Cache. This type of cache could lead visitors to a location near the trig point to gather information (we recommend avoiding the use of Flush Bracket numbers, as these are readily available online), which would then guide them to a final destination further away.

Certainly! We wholeheartedly embrace a variety of cache formats within the Ye Ole Survey Monument Series, including Adventure Labs! It's worth noting, however, that constraints within the API we utilize for generating statistics prevent us from incorporating Adventure Labs finds into our database. To ensure a find is counted, we recommend supplementing Adventure Labs with a bonus Mystery/Unknown cache.

The cache names for the Ye Ole Survey Monument Series will adhere to the following format:

YOSM #1234 Trig Point Hill

The acronym YOSM, representing Ye Ole Survey Monuments, has been abbreviated for compatibility with older GPS displays and to conserve characters in the cache title, considering limited space. Following YOSM is a unique 4-digit series number assigned upon request. Lastly, the cache name concludes with the trig point's name as per the trigpoint:UK website.

To assist you in discovering trigpoints in your local area, we have a variety of helpful maps:


Legacy YSM Locations: Explore all previous locations under the old YSM series by OutForTheHunt here.


UK Pillars: Discover all pillar-type trigpoints in the UK on this map here.


Alternatively, you can utilize the TrigpointingUK website at


If you prefer a more traditional approach, consult Ordnance Survey maps, where trigpoints are marked with a distinctive cyan triangle adorned with a central dot. Happy trigpoint hunting!

Certain legacy YSM numbers at some locations will not be eligible for a YOSM series number. These are:


YSM0077 - has a playground on top of it.

YSM0139 - access problems.

YSM0217 - the farmer has not given permission for access.

YSM0349 - under asphalt.

YSM0362 - under asphalt.

YSM0452 - disturbed by construction work in March 2012.

YSM0483 - under concrete.


If a YOSM series number is issued to any other locations and the trig point gets removed, the cache should be archived. For damaged locations, we will need to assess these on a case-by-case basis to determine whether they can continue to remain in the series.

Requesting the GC code of the cache page prior to getting your YOSM series number serves a dual purpose. Firstly, it enables us to verify GC numbers for publication, especially in cases where we may not be promptly informed. This practice streamlines our process, facilitating a more efficient tracking system for allocations.


Furthermore, this proactive approach effectively 'reserves' the location for you. In the event that others may have a similar idea, the geocaching reviewers operate on a first-come, first-served basis, particularly when it comes to physical locations.

You may have heard us talk about YSM and YOSM numbers. When we refer to YSM, we're talking about the legacy numbering system for outforthehunt's legacy virtual cache which all got YSM numbers. For example: YSM0428 Cold Ashby

The newly revived series are being named as YOSM to avoid any confusion.

Firstly, double-check that your name is capitalized correctly, aligning with your account username on


Secondly, ensure there are no unintended spaces in your name and confirm that you have logged at least one Ye Ole Survey Monuments find.


Please be aware that if you've recently discovered a Ye Ole Survey Monuments cache, it might take a few days for this information to be updated in our statistics.


Should you encounter persistent issues, please don't hesitate to contact us.

Regrettably, bench marks cannot be included in the Ye Ole Survey Monuments series..


The Ye Ole Survey Monuments series honors specific survey monuments used in the retriangulation of Great Britain, a process that significantly improved the accuracy of the country's maps.


Since bench marks were not part of this crucial mathematical process, they do not qualify for inclusion in the Ye Ole Survey Monuments series.

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