South Fortuna-North Fortuna-Sheppards Trail Loop is a 7.8 mile heavily trafficked loop trail located near San Diego, California that features beautiful wild flowers and is rated as moderate. The trail is primarily used for hiking and is accessible year-round. Dogs are also able to use this trail.
This is a great, moderately challenging trail with a decent amount of vert. If you're a trail runner, some parts are steep and require walking/hiking. The declines are similarly steep in some sections so be prepared to brutalize the legs a bit. Mix of different terrain keeps it interesting.
There’s construction and detours on both the weekend and week days. They have a well marked detours, but it will be better when the construction is over. 
Great, moderately challenging trail with a decent amount of vert. If you're a trail runner, some parts are steep and require walking/hiking. The declines are similarly steep in some sections so be prepared to brutalize the legs a bit. Mix of different terrain keeps it interesting. Part of the back section heading back to the trailhead is currently closed.
It got confusing after south Fortuna, I know I took a shortcut back to my car and still ended up with 8.5 miles
I would recommend this trail to anyone looking for a challenging day hike and is comfortable with long steep inclines and declines. No shade on this hike so bring lots of water, maybe even some sort of electrolytes. If you are doing this hike in the hotter months, start early.
Great Trail, much easier if you show up early to avoid the sun. Recommend bringing at least a gallon of water per person. The stairs going up are quite difficult but worth while. This took us about 4 hours to complete. Also beware that there is construction going on at the beginning of the trail.