From the roundabout just west of Aspen proper, take Castle Creek. Drive 12.5 miles to the Castle Creek Trailhead, turning right onto Forest Road 102. From here, the road is dirt and undrivable for most cars. Even 2WD vehicles can make it about half a mile to camp along the creek. A true 4WD vehicle (Jeep, FJ, Xterra, etc.) can continue 2.2 miles from the pavement, bearing right at the junction with Pearl Pass, and making it all the way to 12,000ft at the upper trailhead. This, of course, is all dependent on road conditions and snow.
From the lower trailhead, hike on a clear dirt road. Ascend gradually through a brief bit of forest before switchbacking right and then left. Stay parallel to Castle Creek. There will be cars parked at various points along the road. After 2.2 miles, come to a junction with the Pearl Pass road. Turn right and cross a bridge, continuing up a rocky road (FR 102, poorly marked).
Hike 2 miles up the road through talus fields and forest patches. In the spring there is generally some avalanche damage to trees in this area, so don't be too surprised if there are some downed ones along the trail. Follow the road into Montezuma Basin, reaching the abandoned Montezuma Mine at 12,400ft. The road ends at 12,800ft, as the basin begins to open up.
From here, follow a poorly marked and difficult, rocky trail to the left. Your goal is to hike up to Castle Peak
's northeast ridge. Don't fret too much if you can't find the trail. Aim for the saddle in the ridge and you'll be fine. Hike up steep talus to 13,400ft, at which point the ridge is mellow. Continue up 300 more ft along the right side of the ridge before reaching the ridge proper (13,700ft). Things become more difficult from here. From here, the grade is very steep and the rock very loose. It doesn't quite require scrambling, but it's close. Fortunately the trail here is a little clearer, at least for a little bit, so you can't get too off route.
Hike/scramble up the remaining 500 vertical ft of loose, steep rock. The summit is visible from about 14,000ft, so don't get too amped up for the false one. After the false summit, drop just a bit to a small saddle. The summit's less than 300ft up. Push on.
From the summit of Castle Peak
, it's under a mile to Conundrum, visible right across Montezuma Basin. Of the two apparent summits, the one to the right (north of Conundrum Couloir (Snow Route)
) is the true summit. Descend northwest down loose rock to the Castle-Conundrum Saddle at 13,800 ft. While the trail here is rocky and hard to follow, it becomes easier on the ascent up Conundrum. Hike up steep, rocky trails similar to but easier than the ridge to Castle Peak
. Expect this bit to be absurdly steep. It's probably easier with snow present.The trail will flatten as you approach the false summit. From here, dip down a notch toward Conundrum Couloir (Snow Route)
before climbing up another 50ft or so to attain the real summit.
Adventurous types may opt to ski or glissade down Conundrum Couloir (Snow Route)
while true gluttons for punishment will just do the route in reverse. Either way, it's a hell of a day.
You'll see marmots, pika, and possibly some bighorn sheep and mountain goats. The Elks are home to many-a-bear, although there aren't many reports of them here. When I did this hike I was stalled on the trail by some early morning coyotes. So...be careful!