WARNING TO OTHER HIKERS: DO NOT PARK INSIDE THE GATE!
I have snowshoed this route and wanted to see it without snow, so left Seattle at 9am and arrived around 10:30. There is a gate at the beginning of the road which was unlocked so we drove the first mile or so up the smooth dirt road, just to cut some of the boring part of the hike out. The hike itself was beautiful- wildflowers, views of Rainier, Stuart, and Glacier Peaks, and no other people. However, upon returning to our car and driving down the road we found that the gate was now locked, with us stuck inside. Only about 3 hours had passed since we had driven through this open gate. Apparently this is not a forest service road but a private one. We explored several other branches of the road network looking for a way out, or a person to help us, but all we found were more locked gates. We went back to the main Hex gate and explored on foot looking for a way around the gate. Eventually we found a path that someone else had driven recently (fresh tire tracks). Apparently we were not the first people to be trapped inside. This illicit path around the gate requires SUV ground clearance and AWD. You have to drive though trees down the side of the hill. We walked it first and it didn't look too bad, and our small SUV came through okay. But a valuable lesson was learned. Just because a hike is described on a public website does not mean the public has access to it.
The attached jpeg shows the path around the gate in google earth.