Triangulation Peak to Jefferson Park Loop is a 24.6 mile moderately trafficked loop trail located near Breitenbush, Oregon that features a river and is only recommended for very experienced adventurers. The trail is primarily used for hiking and backpacking and is accessible from June until October.
This is a great weekend backpack and provides for a chance to get up to Jefferson Park while avoiding the busier routes. There are two parts of the loop that as of Sept. 2016 were not well maintained, but passible. The first was the Crag Trail portion, particularly the lower part. The trail disappears for a brief bit, but you'll know you're in the right place when you see the BIG tree crossing the river... and note that it doesn't match the GPS coordinates for the trail (crosses further upstream). The second part is the last bit of Triangulation Peak trail before it intersects Crag trail on the return. It's not bad, but a bit overgrown.