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Sink or Swim (BYO Water)

A cache by Mister Doctor Send Message to Owner Message this owner
Hidden : 04/28/2018
2.5 out of 5
1.5 out of 5

Size: Size: micro (micro)

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Geocache Description:

        Winner of Best Multi Cache
   in the 2018 Victorian Cache of the Year Awards

Estimated time to complete: 20 min
Estimated distance to travel: 700m

Did you know that a can of Diet Coke will float but a can of regular Coke won’t? Or that if you place an ice cube into methylated spirits it will sink like a stone?

These fun facts are all examples of the same rule:
“Objects with lower density will float above objects with higher density”

The idea behind this cache is for you to run an experiment to identify low density fish. Your results will then reveal the final cache coordinates.

The listed coordinates will bring you to Version Three of the Balloon Box, now called the Fish Tank, in the beautiful Gardiner’s Creek Reserve. The fish you will find there are filled with either glycerol or water (see Appendix for details of the previous versions).

  • You will also need to bring at least 600mL of water
    (extra water is available nearby at S 37° 50.572 E 145° 7.141 or S 37° 50.705 E 145° 6.876 (listed as waypoints))
The densities of the materials are as follows:
  • methylated spirits (density = 0.79 g/mL)
  • fish plastic (density = 0.90 g/mL)
  • water (density = 1.00 g/mL)
  • glycerol (density = 1.26 g/mL)

You do not need to take anything apart to run the experiment - simply add water, the more the better! The fish tank may also need a wee shoogle to help with separating the fish. Please empty out the water once you have finished.

In case you have any technical issues, here is a little guidance in checking your results:
S 37 50.ABC E 145 07.DEF
checksum: A+B+C=10
checksum: D+E+F=12

The first version of this cache used balloons filled with either glycerol or methylated spirits. It turns out methylated spirits and rubber balloons aren't that compatible - who knew? In the current version, fish have replaced the balloons and are filled with either glycerol or water.

***CONGRATULATIONS to geo_jas and Spladem on the joint FTF***

Additional Hints (Decrypt)

Yvfgrq: 700 zY pbagnvare (ybj qrafvgl)
TM: svyz pnavfgre (uvtu qrafvgl)

Decryption Key


(letter above equals below, and vice versa)



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Coordinates are in the WGS84 datum

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