Most folks enjoy the view of Spiral Butte from afar, whether they're skiing downhill or cross-country at White Pass, or hiking along other trails in the area. But if you want to tackle this trail, it makes a good diversion for those camping at Dog Lake, or simply looking for a day hike in the area.
Start at the Sand Ridge trailhead just off Highway 12. This trail (actually a dirt road for a short distance before it narrows into an actual trail) climbs a bit through Ponderosa pines, switchbacking for 2.3 miles before you arrive at a junction with the Shellrock Lake trail.
Hop onto the Shellrock Lake trail, and after a mile here, arrive at the junction with Spiral Butte Trail. As you climb up the Spiral Butte trail, the Ponderosas are exchanged for Doug firs and other evergreens, following you nearly all the way to the summit. This route is steep for about a half mile and then it moderates, meandering through overgrown brush as the trail sweeps left around the flank of the Butte.
Along this traverse, it is possible to see the White Pass ski area across the way, as well as Dog Lake below. Further in the distance are Rimrock Lake, the Goat Rocks, even Mount Rainier on a clear day.
Note: Spiral Butte is actually a cinder cone, which means the trail is sandy and can make for slow hiking. It's also a dry trail. Take all the time you need and bring all the water you'll want.