This walkway isn't too big of a secret, although I bet most people haven't been on it before. This is a bit different from the others in this series, because this one has a puzzle to solve before finding the cache.
I was contemplating some new caches that required a lengthy hike to get to and came up with the following:
GPS + (K * CACHE) = HIKING
There are multiple solutions (thanks to Jif and Kablooey for pointing this out to me). To help you narrow down the possible solutions, use only solutions that have K < C
The cache can be found at:
N 37 15.ISC W 121 56.SGS
The cache is a small M&M plastic container. It contains a cache pen, a log sheet/stash note and a few VERY small trade items. Think SMALLER than a marble.