Overview: An off-trail canyon that takes most of a day to explore, likely done as part of a 3+ multi-day backpack trip.
Warning: This is a pretty remote place, don't get in over your head. The park service does not patrol this area. Avoid if rain is predicted!
History: Haunted Canyon is apparently named in relationship to the fact it merges with similarly themed "Phantom Canyon". And why was Phantom Canyon named this? Well, for Phantom Ranch. And why did the ranch get that name? Apparently Mary Colter thought the word "Phantom" elicited thoughts of romantic nights. Careful about spending too many nights in the backcountry, folks!
More recently, a flash flood killed a few backpackers in the late 90's, so be careful!
Hike: From Overhang camp, about a quarter mile south of the junction of Haunted Canyon/Phantom Canyon, follow the creek north and find where it crosses over Phantom Creek. A good trail appears on the other side, becomes faint briefly, and then takes pretty good shape again. It will lead you into Haunted Canyon (south of Haunted Creek at this point). Shortly, the trail uses a sturdy log to cross over to the north side of Haunted creek and gain a little elevation to get away from Haunted creek a bit. The next mile or so is fairly easy to moderate hiking if you can manage to stay on the route. It slowly degrades as it gets a little faint, and gradually gets pretty high up on the north/west bank of Haunted Canyon. About a thousand feet before you get to Haunted Spring, the trail appears to have been washed out by a landslide. I'd recommend you try to maintain your elevation, if possible, but there are about 3 gulleys to cross. It's pretty much a free for all, and going down to the creek will be pretty, but really gnarly (brushy).
Once you make it to near Haunted Spring, you will observe the canyon split. You can follow a short tributary to a small spring directly north, follow the main flow of the water to haunted spring, or continue up the dry part of the main canyon. First, I'd recommend you follow the main flow to find the Haunted Spring source. It is fairly impressive how much water is coming out of the ground just about 150 ft above the main bed of the canyon.
After seeing the source, return to the main bed and begin rock-hopping up-canyon. Travelling is fairly easy from here on. There is no trail and only a few rocky sections present some moderately easy boulders/climbs. Just stay in the main bed and continue heading up-canyon. The canyon has a few interesting features, though nothing to write home about. About halfway up you will find the monument of Haunted Canyon. Stay to the right of it, headed upcanyon, to stay in Haunted Canyon. As you near the head of the canyon it will get a little narrower, and finally split into a few distinct streambeds. You can wander around in here but you are basically at the end, trapped beneath dryfalls in the redwall where 3 tributaries come together. A possible redwall route can be seen for those who are rock climbers and brought some trad gear. Interestingly, you are only about 0.7 miles from Widforss point, which is way above you. The views looking up at the point are fairly neat.
Turn around and head back. If you are sharp eyed you will find a fairly large arch on the west side of the canyon. Continue on past it, get back to the monument, pass it to get back to the wet half of the canyon, manage your way through the abysmal 1000 ft section, and retrace your steps back to overhang camp.
Water Sources: The canyon is wet below Haunted Spring, which is not quite halfway up the canyon. The flow is fairly turbid, so it isn't perfect for filters, but it is fairly good. Above this the canyon is bone dry, so take plenty of water with you.
Camping: I only observed one possible decent campsite in Haunted, though some hardship sites could be made. All were within the first half-mile. Most will camp at Overhang camp, which is about a quarter mile south of the junction of Haunted and Phantom on the west side of Phantom Creek.