You must have a good map to navigate in this wild region. The road is accessible to passenger cars if care is taken, but go well prepared. Leave with a full tank of gas from Emery or Green River before heading out on the back-roads.
There are three possible exits to take off I-70 between Emery and Green River. The easiest driving route to follow may be from Exit 97. Roads from Exits 89 or Exit 105 will also lead you to the same area.
From Exit 97, follow the road south for about 9 miles to a four-way junction. Keep straight and follow the signs/roads to Moroni slopes. There are many junctions, but drive past Hebes Mountain and between the two Cedar Mountains on the map, and then two the Moroni Slopes catchment and Horse Heaven Reservoir. This is the trailhead.
Wading the canyon with packs and climbing gear.
From the trailhead (Horse Heaven Reservoir), follow the faint vehicle track along the rim of the South Fork. You must find a route into the canyon. There are several possibilities, and all have some challenge to them.
After you find a route into the canyon, follow the canyon down to the confluence with the North Fork and pool mentioned above. There is one major obstacle 2/3 of the way down the South Fork. You can pass the major drop off on the left (north) side. This is a fair challenge, but if you have trouble here, seriously reconsider heading further down canyon. Now that you are at the confluence, you must swim the mentioned pool. Continue down canyon. There are several minor, but fun bouldering obstacles.
Soon you will reach a huge boulder jammed between the canyon walls which cannot be bypasses neither can it be negotiated with out a rope. Rappel off the boulder using natural anchors. The drop is about 35 feet. Continue down canyon.
IMPORTANT: Keep an eye out for some exits (there are several, but none are easy), in case you must retreat if the next section of the canyon proves too difficult.
You will eventually reach a section of the canyon where the drainage drops through several huge potholes. This is where the canyon gets difficult. There are six potholes right in a row that must be negotiated. Rappel down the first two with the same rope. The others can be downclimbed. One of the pools can be difficult to climb out of, so be prepared! You must swim several of the potholes. Continue down canyon. After a short distance, you will reach another section of the canyon with five huge potholes. We used natural anchors here (a walnut-sized chockstone), but since then, some low-skilled climbers have bolted the drop. I can't guarantee the bolt will be there in the future, so you should certainly learn natural anchors before dropping into this canyon! This section of potholes has several 5th-class down-climbs and much swimming.
Continue down canyon until reaching another set of potholes. This is the crux of the canyon. You must do a hairy traverse around a deep, but not very wide pothole, taking care not to fall in (which would leave you trapped in a over-your head pool with vertical or overhanging 20 foot high walls on all sides!!). Immediately after the deep "keeper pothole" is a 80-85 foot drop into another "keeper pothole". This is certainly the crux and can be a real bear of an obstacle. After rappelling the 80-85 foot drop into the pothole, swim across and climb out the other side. The climb out can be difficult, especially if the water is at such a level where you have to start the climb by treading water! This is where a life jacket comes in handy. Teamwork and helping each other out of the pothole is usually required. Take a deep breath. The last technical obstacle is just beyond. There are a few swims including one 100 feet long before reaching a chockstone which forms a 10-foot drop. After rappelling off the drop, continue down canyon until you can exit to the rim on the right (south) side. Exit the canyon and follow the rim of the main canyon and then the South Fork all the way back to Horse Heaven Reservoir. You survived!! Unless you're Superman, this is a very long day.
Rapping into a pothole.
Two 50 meter ropes (and maybe a few short ones), a climbing harness, at least 100 feet of sling, perferably more, 20 descending rings, an aider, a headlamp, a life jacket, and drybags for all gear. Also recommended: A wetsuit in cool weather, and a bolt kit, but please only place a bolt in a real emergency!