The waypoint is where you will probably want to leave your
"Shaguar" for the final stage; it's just a few hundred metres from
there to the cache and back. The cache would also be a nice short
bike tour from Kehl (or Strasbourg), in which case the waypoint
would be a good place to get off your bike.
First, print out this top-secret
code sheet. Make sure that it's the right size: the main
rectangle should be 129mm wide and 207mm high.
Next, you need to obtain the names of the two "keycells" on the
sheet. Each cell name consists of a letter (A-Z) and a number
(1-50). The keycell names can be found in Plan
d'Eau de Huttenheim and Sentier
des Casemates. Each cache contains the name of one of the
keycells, and a puzzle to find the other one. So you can either
visit both caches, or visit just one and solve the puzzle (which
some people will find hard).
Now add the numeric components of the keycell names, to get
X. For example, if the keycells are D23 and J34 (they
aren't), then X would be 57 (it isn't). Then
calculate:
nnn=((X*5)-37)
eee=((X*15)-38)
Take the top-secret code sheet and the keycell names to
N48º33.nnn E007º48.eee, where you will find (in a
big, old, "scary" tree) the "high-tech equipment" which you need to
get the final cache coordinates.
Oh, and when you log your find, don't reveal anything which
might be useful for Dr. Evil!