The entrance of the park is N 48'50.023 W 122'35.094. When you get to way point one, Go up and enjoy the view. Come down to ground level and find the coordinates to way point two.
To find way point two, you'll have to take a walk on the boardwalk. Find the right bench at way point two and you'll find the coordinates to way point three.
To find way point three, go up and see another view. Come down to ground level to find the coordinates to the cache.
When you get close to way point four (where the cache is) find three alder trees that are very close together and you will find the cache.