- Location: Silverado, in the foothills of the Santa Ana Mountains. From the 55 Freeway, take the Chapman Ave. exit and head east for a total of 7.7 miles (Chapman becomes Santiago Canyon Road en route). Shortly past Irvine Lake, look for the Augustine Staging Area, turn right and park as directed in the lot. From I-5, take El Toro Road and head northeast for a total of 14.2 miles (El Toro becomes Santiago Canyon Road). The Augustine Staging Area is on the left, 1.8 miles past Silverado Canyon Road.
- Agency: Irvine Ranch Natural Landmarks; Orange County Parks & Recreation
- Distance: 9.8 miles
- Elevation gain: 900 feet
- Difficulty Rating: PG-13 (Distance)
- Suggested time: 4-5 hours
- Best season: All year (hot during the summer); accessible only during specific times (check Irvine Ranch Natural Landmarks link above for schedule)
- Recommended gear: sunblock; sun hat; hiking poles
- Dogs: Not allowed
- Cell phone reception: Good at the staging area and on the ridge; weak for most of the route
- Restrooms: Chemical toilets at the trail head
- Water: None
- Camping/backpacking: None (nearest is at O’Neill Regional Park)
- More information: Limestone Canyon info here; trip descriptions here and here
- Rating: 7
Updated October 2018
Estimated to be 30 million years old, the Sinks is the most recognizable feature of Limestone Canyon and one of the most unique geological formations in all of Orange County. In 2016, a new viewing deck opened on the eastern lip of the Sinks, providing excellent views. The site can be visited on open access days (usually the first Saturday of each month) or as part of a docent-led hike through the Irvine Ranch Company. The network of trails in Limestone Canyon Regional Park allows for several possible routes to and from the Sinks. The elevation gain and distance listed above reflects the typical route taken on the docent-led hikes, which can also be followed individually on open access days.
Begin by following dirt Limestone Canyon Road southeast from the staging area for 1.1 miles through an oak and sycamore dotted meadow, passing by several remnants of the area’s ranching past. Turn left on Limestone Spur which climbs to Limestone Ridge, your trail for the next 2.5 miles. Limestone Ridge makes a steady ascent with a few drops as it heads south, paralleling Santiago Canyon Road. Traffic noise is the only drawback of this leg of the hike, which features impressive views of the Santa Anas to the east and Limestone Canyon to the west. After about 2 miles on this trail, the edge of the Sinks come into view. You drop down to a service road and follow it past a junction with Limestone Ridge Road (your return route) and to another junction, about 4 miles from the start. Here you can enjoy your first up-close view of the Sinks.
If you are hiking on your own and are short on time, you can continue a short distance up the road to the viewing deck. An enjoyable detour, however, is to head left on the Markel Spur Road which soon becomes a narrow single-track, twisting its way down a ridge into the shaded reaches of Hangman Canyon. Head right up Hangman’s Tree Road (once thought to be the site of the tree where members of Juan Flores’s gang were hanged; the name stuck even after it was found to be inaccurate as the true location of the tree is several miles northwest). A short climb brings you to the viewing deck, where you can enjoy an all-encompassing view of the “Grand Canyon of Orange County.” To the southwest, Agua Chinon Canyon opens up to the housing tracts of Irvine, Tustin and Orange – a reminder of how close this area is to civilization. If visibility is good, you can see the ocean.
For a varied return, follow Limestone Ridge Road north, passing the junction with Markel Spur Road and climbing back to the previous junction. Turn left and follow Limestone Ridge Road downhill for 0.4 mile to Limestone Canyon Road. Turn right and follow Limestone Canyon Road all the way back to the staging area for a pleasant if not particularly eventful 3.4 miles.
Text and photography copyright 2018 by David W. Lockeretz, all rights reserved. Information and opinions provided are kept current to the best of the author’s ability. All readers hike at their own risk, and should be aware of the possible dangers of hiking, walking and other outdoor activities. By reading this, you agree not to hold the author or publisher of the content on this web site responsible for any injuries or inconveniences that may result from hiking on this trail. Check the informational links provided for up to date trail condition information.