The cache isn't located at the posted coordinates, but you can start your search there (recommended) or anywhere inside Marymoor Park.
To find this geocache, make sure you have a Wherigo enabled device such as a phone. Install the official Wherigo app if you are on iPhone, or the WhereYouGo app if you are on an Android device (other Wherigo players also exist for android). Download the Wherigo Cartridge and input these numbers into the player:
716327
472013
680132
Unlike the usual wherigo, the Reverse Wherigo will give you the distance to the next waypoint, but not the bearing/direction. It is up to you to periodically query the wherigo to check your distance to the final and deduce the direction as well. Good luck!