Getting there: This trail begins at the Inspiration/Seven Falls trailhead. This trailhead can be crowded and parking is nearly non-existent. There are a dozen official spots on the side of the road and in small turnouts spanning a quarter mile down the road. The trailhead is in a residential area so please be conscientious of that.
Directions: The first mile of Tunnel Trail South is a paved road that climbs steeply from the trailhead. At this mile point, the trail T's with a dirt road. At the dirt road, take a left and follow signs towards Seven Falls. Take an immediate right (after 100m), depart Seven Falls Trail
and continue uphill. This turn is not signed very well and is easy to miss. This 1.5-mile section is very rocky and steep.
At mile 2.5 there is a three-way intersection. Stay left and follow signs to El Camino Cielo, the trail on the right takes you down into Rattlesnake Canyon Park. The trail gets flatter and less rocky and the geography opens up to give great views of Santa Barbara and the Channel Islands. At mile 3.1, there is a crag with a few faint climber trails that are easy to mistake for Tunnel Trail. Generally stay right and continue uphill. If you take the wrong trail, you'll cliff out pretty quick and realize your mistake. After this section, the trail is nearly flat and very well cleared of brush. The trail terminates in a dirt field well traversed by dirtbikers and a hundred meters beyond this is the road.
Overall Impressions: The trail is technical, steep, and rocky. During the spring and summer, it can be overgrown with brush and hot. Far too many people use the trailhead and the first mile (shared with Inspiration Point/Seven Falls) while very few people use the section from the Seven Falls Trail
up to the climber's crag. Cell phone reception is generally good. I took it while passing through town and wouldn't recommend it in and of itself. I think the best utility of this trail part of a loop encompassing Cathedral and La Cumbre Peak on the way up and Tunnel Trail on the way down or as a connector into Rattlesnake Canyon Park.