Here's a trivia question to toss out during your next trail party: The Iron Horse Trail and Washington's other cross-state trail, the Pacific Crest Trail (PCT), intersect but never touch. Why not? Answer: Because the Iron Horse Trail runs through the 2.3-mile-long Snoqualmie Tunnel while the PCT rolls up and over the peaks south of Snoqualmie Pass. When you head out to explore this dark Iron Horse section, be sure you bring a flashlight--and a headlamp. In fact, make sure every person in your party has a primary light and a backup--this is not a hike you want to do without light. The tunnel is long enough that you'll be in deep, total darkness much of the way. And it's easy to get turned around inside. I've seen savvy hikers bouncing like pinballs inside the tunnel because they couldn't get themselves headed straight down the tunnel after losing their light.

Find the trail on the south side of the parking area, and turn west to hike along the open railroad trail until you reach the eastern portal to the tunnel. Stop and recheck your flashlight batteries before diving into the darkness.

You might also want to pull on your sweater before you go in so you don't have to fumble in the darkness. It can be 100 degrees Fahrenheit outside on a bright, sunny day, but underground the temperature drops into the 50s. The dampness makes it feel even colder.

Also, note that the tunnel is gated November 1 through May 1 for safety reasons. Giant icicles form in the tunnel during the cold winter months, creating massive spears that could threaten the unwary.