This probably should have been my first trail specific post seeing as it spans two majors parks and is an easy trail for riders of any skill level (as a former trail guide, I used to take people who had never ridden a horse before on this trail), and is a good trail to do in pieces for the horse new to trail riding, so here goes.
This Trail is a long one, especially if you ride from end to end. The trail head begins at Cannon St. just North of where it intersects with Santiago Canyon Rd. and runs through Santiago Oaks Regional Park, up and over the hills that surround the Dam between Santiago and Irvine Regional, through Irvine Regional Park on the South side, working its way into the center of the park, then crossing the creek bed to the North/East side by Peacock Hill Equestrian Center, continuing along the creek bed until finally stopping at a usually empty gravel parking lot at the far East of the Park by Peter’s Canyon Rd. It is not an overly complicated trail, no real twists or turns and staying pretty much flat for the length of the trail (except when crossing over the dam). It is a good trail if you want to conquer a lot of ground in a few hours.
I would recommend picking up the trail at the entrance to Santiago Oaks, rather than the entrance at Cannon, which follows Mabury Ave. East. There are some spots not recommended for horses (there’s a sign saying so and everything) when going this back route into the park, and while not super difficult, it is narrow and awkward with bare smooth rock and sudden ups and downs that make it somewhat tricky and annoying if your horse or you are inexperienced. You can also enter halfway at Cardiac Hill. When you ride into Santiago Oaks, it is the first trail you are placed, making it easy to find. The trail runs East from there, staying easy to follow with posted signs and its relatively straight path. It’s a wide flat trail that is easy to ride on with bikers and hikers, but beware of dogs, many people like to let them off-leash in this park.
Once you cross over the dam, at least to the South of it, you follow the valley section of Santiago Canyon/Irvine Regional and ride along the Holy Sepulcher Cemetery. If you like to lope or gallop your horse, this is the place to do it. Its typically open enough that you can see people coming up in front of you and as mentioned is relatively flat, though I recommend doing a walk through on your first visit so you can get a better idea of the terrain (there are some small dips and rises).
This trail is fairly uneventful to be honest, but it does provide nice wide views of the park. Its open and exposed, so wear your sunscreen, and it can get hot in the summer. If there is a river in the winter and spring, you get to ride across it and along it if you stick to this trail, so that can liven it up more. I have spotted deer from this trail and occasionally coyotes, but I usually see more on trails that are centered in the park.
There is a water trough along the trail, closer to the stables, next to Mwd Rd. where there is some shade to rest in (if you’re a horse named Kitty, you may attempt to go swimming in the trough, this is not recommended). Once you cross the creek bed, it is not super maintained as you go East, so it’s usually better to just take Peter’s Canyon Rd. which it eventually dumps into, or break off onto Tonyon Trail or Horseshoe Loop.