To access Bonanza King, you first have to find state highway 3 that connects Yreka and Weaverville. There is a short cut road from Interstate 5 that connects the Castle Crag area to highway 3 and there is another connection from the town of Weed to highway 3.
About 4 miles north of the upper end of Trinity Lake there is a national forest campground called Trinity River Campground. The campground is on the west side of the highway, but you will want to turn east towards Bonanza King. This is forest road 38N35 and parallels Scorpion Creek for a ways and then climbs steeply up to Scorpion Lake and then on to the fire lookout. This road is gated and closed from October 30th thru May 1st, so plan your trip accordingly. Of course, you can always walk the road, but the snow may be quite an obstacle, and there is about 4,400 ft of elevation gain in 10 miles.
After visiting the fire lookout, drive back down the road to the saddle where the road forks and park. This is where you start your hike.
The saddle where I parked is at about 6,640 ft. The entire route is cross country with no trail. Head up the rounded slope to the north between the fork in the road. The slope is easy hiking with some minor short brush. Before you reach the top of this hill, traverse to the right towards the timbered saddle ahead.
At the saddle (elevation 6,900 ft) you can chose the route you want to hike. The easy way is continue through the saddle down to the small valley on the west side of the ridge line. This involves losing all the elevation you just gained, but it is easier and quicker. The alternative is to hike the ridgeline north. Hiking the ridgeline isn’t technical, it is just slow and tedious finding a route from one obstacle to the next. There is kind of a rough climber’s trail most of the way. I took the ridgeline going out to the highpoint, then descended to the little valley on my way back to the trailhead.
As you proceed out the ridgeline, you have to go beyond the large rounded highpoint (7,036 on the topo) to the next more pointed protrusion north. There is a large cairn and a summit register on the highpoint.
Total hike is less than 1.5 miles and gains about 1,000 ft with all the ups and downs. It took me almost 2 hours for the hike.