Canyons are inherently risky. Flash floods occur without notice on sunny days. Technical skills & surrounding topography knowledge required yet does not eliminate risk.
This one's got it all
Overview: This is an exceptional reverse lasso loop taking off from the first "hairpin" curve of the Catalina Highway. Go off route up beautiful Soldier Canyon to the falls. From here scramble up the canyon wall to meet the Soldier Trail and take it out to Prison Camp to see some nice little falls, then come back to the Catalina Highway (taking in spring wildflowers along the way) and walk the highway around 1/2 mile back to your car. Along the way (in season) you'll see creeks, waterfalls and flowers galore...what are you waiting for?
This hike requires some familiarity with the land, or at least studying the appropriate topo maps. The hike up Soldier Canyon is an off route canyon bushwhack as is the scramble up to Soldier Trail.
Hike: From the road start right up the canyon in whatever fashion works best. In the spring there may well be flowers and water flowing everywhere. The takeoff point is the canyon that comes feeding in from your right. You can actually see it from the road. It is about 0.3 miles to the mouth of this canyon, again, which is on your right. This is Soldier Canyon. Immediately there is a pretty significant sheer wall, which may have a very narrow fall in it. You can scramble up the left side of this wall and gain the top of the fall, only to see a more gorgeous cascade right above it. Take a million pictures if it's flowing and then climb up the left side of this too. There is some exposure here, as there is on much of this route so please be very careful. Once above this two-tiered obstacle you have smooth sailing for a little while. Pick your way up and along the canyon, which occasionally narrows down nicely and towers above you. There may be a creek flowing at the right time of year with whimsical little falls everywhere. This section is picturebook. You are rock-hopping most of the way.
At about 1 mile a narrow, rough side canyon comes feeding in from the right. You can see a rugged pile of massive boulders to your left that seem to be blocking your way up the main canyon. You do need to make the left and stay in the main canyon. Though it seems impossible, you can climb up the left side of this mess. It's a rough, bloody scramble but there is a way. Eventually the tiniest use path dumps you in underneath the rocks. A very narrow, knifelike rock leads you up about 8 feet or so and then you are free. It seems this is the only way up and if you just start right and exhaust all your options until you are on the left side of the pile you will find it. Be careful here, a fall would be BAD. Climb up more piles until the canyon levels out a bit. From here it is about 0.7 miles or so of more easy canyon climbing and creek crossing until the canyon ends at a vertical wall. There are two beautiful thin falls here. One in front, that is two-tiered and a second multitiered fall further back to the left. This area is just peaceful and wonderfully secluded.
To complete this as a loop hike, your goal is to now find a suitable spot to your right, along the south wall of Soldier Canyon to climb straight up the canyon wall to get out and onto the shelf above you. There is no correct way, but there are several steep drainages feeding down to chose from. The closer you start your scramble to the falls, the closer you will be to the trail when you top out. Be careful here, you are climbing straight up a wall with loose footing and a fall could be quite bad. It's gonna be about 350-400 feet straight up the canyon wall. I followed the closest drainage making little zig-zags up the wall and had no problems. As you top out you will see some rocky ledges and shelves, the telltale sign you are close. Gain these rocks and look ahead and to your left for the Soldier Trail coming up the opposing ridge to cross over a small saddle to your left. If you plan this correctly you will be within 5 minutes of the trail. The Soldier trail is going to cross over Soldier Canyon right above the place where it severely narrows down to force you out of the canyon in the first place, so keep this in mind and in your sights and you will find the trail.
From here, I would recommend following the trail out to Prison Camp. The trail breaks to the right, down from the little minor saddle where you join it and descends a little to cross a relatively flat section of the canyon. Again there may well be water flowing, though crossing is pretty easy. This is a nice riparian area with all sorts of small trees. It's green and lush. If you break off the trail and go left down the canyon a couple hundred yards, you can see where the walls quickly choke in. Follow the right side of the canyon. It immediately closes in and forms a more narrow chute. If you are careful and climb down on the right side this actually ends up forming a beautiful slot canyon that you can climb a ways down before essentially cliffing out. You can climb down and swing back to your left under a ledge to get a great view of water flowing down the slot. BE CAREFUL here, a fall would be BAD.
Back at the crossing go only a short way before crossing again then climbing away to the left. Steeply you access a nice ridge and hike along the grassy trail towards a prominent ragged peak. The canyon comes back to your left and if the season is right, you can see a couple of nice falls again. Soon the trail breaks to your left, descends and crosses over the canyon. It then descends more to the signed intersection with the Molino Trail and Sycamore Reservoir at the Prison Camp. From here you can cross over the wash and pick up a little use path on the other side heading down and to your left back into the area where the canyon narrows down. Within this little section lie many little falls and pools, with beautiful secluded areas for a break. This is a popular area with rockclimbers too. It's definitely worth the short trip here.
Take the Soldier Trail back to the trailhead off the Catalina Highway and walk the road about 0.5 miles to your car, parked at the hairpin curve to complete the loop.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.