This is a great trail. The "Tunnels" have been a longtime favorite with riders in the area. Sadly, they were closed for many years. but were reopened in 2015 as part of a new plan for the Del Mar Mesa Preserve.
Tunnel #4 drops into the tunnels from the top of the mesa. From the bottom, you can head West or East.
A great singletrack, tree-covered trail. The trail itself is steep in some sections and rocky in others. While ample tree cover provides shade, roots are also an obstacle on this trail, so keep an eye out for them! Between rocks, roots, and the grade, this trail will test your skills.