Silver Lake, sometimes Silverlake, is an unincorporated community in Cowlitz County, Washington, in the southwestern portion of the state. Silver Lake is located 6 miles east of Castle Rock along Washington State Route 504, which is also known as the Spirit Lake Memorial Highway. The area considered Silverlake is about 6 miles east of Interstate 5 and is approximately 50 miles from Portland, Oregon, to the south and Seattle about 110 miles to the north.