This cache takes you to within arms length of one of the many monuments across Canada that make up the Canadian Base Network. This particular monument is known as Pier 18, or more formally as CANADIAN BASE NET MONUMENT "55118.18" (NGDB NO. 85X406). The container is a 15cm x 15cm x 5cm (6" x 6" x 1.5") Lock & Lock box near the post (camouflaged of course).
The Canadian Base Network program began in 1994 and is a collaboration of many different government agencies, both Provincial and National, to establish ground monuments at regular intervals across the country for the purpose of survey control. Essentially these monuments are checkpoints for surveyors that ensure that everyone is measuring with the same stick.
Source: http://www.geod.nrcan.gc.ca/network_p/cbn/index_e.php
So Why Did You Bring Me Here?
The accuracy of these markers is amazing, with most being placed with only a centimeter of possible error; Pier 18 is measured to within 1 millimeter. The really cool thing about these markers for geocachers is that we can test out our GPSr units against a known position with incredible accuracy. Haven't you ever wondered how accurately your unit is measuring?
So How Do I Test My GPSr?
The not so cool thing about these markers for geocaching is that the units of measure the government uses are not the same as we are used to. The markers are located using either UTM coordinates or Latitude and Longitude based on the NAD83 datum projection (everything in the geocaching world is supposed to use the WGS84 datum) {datums are explained in more detail below}.
Essentially what all this unit and datum hub-bub means is that we need to either convert the government listed location from NAD83 to WGS84 (which is what the cache coordinates above are) or, to get an even more accurate read (eliminates averaging that happens with conversion), we can change the units in our GPSr and re-enter the waypoint. To change the units in your GPSr just go to the setup menu and find the units section, then just change them to either UTM or NAD83 and enter one of the coordinates below. Just please don't forget to change the units back to WGS84 before you head off to do some more caching. Entering the elevation information (658.596m) is a critical step and will help to give you a more accurate reading {Hey, test out your altimeter too if you have one of those fancy units}. After entering the data just set your GPSr on top of the post and let it sit there averaging for a bit (it could take some units quite a long time to settle on bad reception days so be patient).
The government published location for Pier 18 is:
Latitude : N55° 11' 13.6015" +/- 0.001 m (NAD83)
Longitude : W118° 32' 19.4245" +/- 0.001 m (NAD83)
UTM : Zone = 11 N = 6116693.49 m E = 402032.44 m
source: http://csrsjava.geod.nrcan.gc.ca/csrsjcpe/GSDreportsEN?user_name=name&querytype=CBN&key=85X406
So What Is All This Datum Mumbo Jumbo?
Great question, glad you asked. Essentially what coordinate systems do is that they overlay some sort of grid pattern over the entire Earth. Finding a position on the Earth becomes as simple as reading a graph, just find X and Y (this would represent a 2-D fix). The complicated part of this comes from the fact that it is really hard to fit a flat grid on a round thing (go ahead try it on your globe or tennis ball or friends head, you will either have to cut the paper or get some wrinkles). To make matters worse Columbus was wrong twice: not only did he not find India but the world is not in fact round, it is roundish. It appears that the Earth is actually smaller around East to West than it is North to South (the spinning force apparently has something to do with this). This now is finally where datums come in...
All of the different datums (and there are many of them) are created based on different ways in which their creators using the latitude and longitude coordinate system have dealt with fitting a big flat grid on a roundish Earth and on different estimations of how big around it is. Another example of how the flat thing on a roundish thing problem has been solved in another system is the use of 'correction lines' in our own township and range method of dividing up the landscape.
In the end what all this means is that if someone measures a position using one datum and someone tries to find it using another datum they may not be talking about the same physical location on Earth (this is called a datum shift). That is why I warned you that our government has used NAD83 for this project (which they use for most of their work) and to ensure that you switch things back to WGS84 before you leave.
If you read this far, thank you. I hope you have learned a bit about all of this. If you want to do some more reading about this stuff (Hey, maybe you are a glutton for punishment), I have some related links below.
P.S.
There won't be a test on any of this.