The Blue trail is easily accessible, is great for hiking/biking, and has some great views across the lake.
Here are links to the official park site & to a trail map:
http://www.mercercountyparks.org/parks/mercer-county-park
http://www.jorba.org/sites/default/files/2010_SMART_trail_map_0.jpg
There's a famous painting by Edvard Munch called The Scream. It was painted during a time when the artist described himself as nearly going insane, like his sister who was committed to a mental instatution. I hope this cache doesn't drive you insane as you are drawn to the mouth of the cache.
Hope you didn't lose your pen.
ENJOY!