Diablo Canyon hike is not on a marked trail, but rather follows an arroyo (dried up river bed) from the parking area all the way to the Rio Grande (3 miles one way). The canyon itself is quite spectacular. This hike was so different from the hikes we've been doing in the Santa Fe and Taos ski basins. Where those hikes are shaded by Ponderosa pines with views of green mountains, Diablo Canyon is definitely a desert environment with close to zero shade. We completed this hike on an August morning. We were at the trail by 9am, so we had some shade in the actual canyon. However, we got through the canyon pretty quickly. Probably 2 1/2 miles of the 3 mile one way hike is not in the canyon. We roasted. We enjoyed the hike, but I think it would have been more pleasant on a fall day.
If you are completing this hike in the summer, please remember lots of sunscreen, a hat, sunglasses, and plenty of water. As they say in New Zealand, "slip, slop, slap." Slip on a shirt, slop on 30+ sunscreen, and slap on a hat. Add plenty of water to your pack, and you'll be ready for Diablo Canyon!
Also, make sure there are no thunderstorms in the forecast or suspicious looking clouds in the area. I wouldn't want to be in the canyon during a flash flood.
Getting to the hike wasn't tricky, but it did require driving 8.6 miles down Old Buckman Road. It's a dirt road with some sandy parts. We had good directions in our "Day Hikes in the Santa Fe Area" book by the Northern New Mexico Group of the Sierra Club. This book is the bible for day hikes in this area. So far, I'm super impressed with this book and it's well worth the $17 we spent on it. We ended up buying it at this great little bookstore - Garcia Street Books - off Canyon Road, but they also sell it at REI.
We arrived at the parking area and were the only people there. It stayed that way for the entire hike. We followed a little path to a break in the wire fence and made our way into the arroyo.