The Snoqualmie Tunnel is part of Iron Horse State Park, a 1,612-acre park that was once part of the path of the Chicago-Milwaukee-St. Paul-Pacific Railroad.
The tunnel is what’s left of a section of track and is now open to hikers. The tunnel itself is a dark 2.3-mile stretch which burrows straight through a mountain. Cool and comfortable, even downright cold at its center, the tunnel requires hikers to wear layers for warmth. The closer you get to the middle, the smaller the light at either end becomes, until you’re completely surrounded by drippy, echoing darkness.
The trail is flat and straight so it’s an easy, if long, walk and there are picnic benches at the far end with a spectacular view of the surrounding mountains. Flashlights or headlamps are a requirement for getting through safely, however, as hikers have been known to lose their sense of direction in the subterranean dark.
Don’t expect to navigate the tunnel in winter. During the colder months (November 1 through May 1), the tunnel is closed to all traffic due to dangerous icy conditions: