Theory
Riihimäki Geochallenge is half of the dual cache system,
the other part is Hyvinkää Geochallenge. Both
caches
can be logged separately, but in order to find them
you have to collect information from the both cache pages.
Finding this cache system starts with a mathematical homework.
The cache twins are defined by two points on the highway #3 from
Helsinki to Tampere. Riihimäki reference point is defined as
N 60° 40.269, E 24° 46.632. The bearing from this point to
both cache locations
is equal (193.82 degrees). The angle value is true bearing in WGS-84
coordinate system,
zero degrees is pointing to north along the current longitude
line and 90 degrees is pointing to east along the current latitude line.
Warning: The reference north of the Finnish coordinate
system YKJ is not parallel with WGS-84 north in this area!
Action
The plastic container is hidden rather near the top of the cliffs. The place may be hard to reach, but you really don't have to do anything dangerous.
Unlike in Usmi, here we can't guarantee good trails leading to the cache.
There is a river at the bottom of the canyon. It's not very amazing, but
however,
if you are approaching the area from Usmi, you have to cross it. (There is
also a
bridge somewhere.)
Have fun!