The cache is NOT at the posted coordinates.
This is a bonus cache for completing my Adventure Lab Cache "My Mountlake Terrace Tour". To obtain the final coordinates you need to complete the Lab Cache. Pay attention to the journal entries at the lab caches. There you will be given the coordinates for this cache.
This is a popular city park, and part of a disc golf course. Please use your utmost discretion while retreiving the geocache.
Congratulations to Qaz&Kids for FTF!