Anyone who has ever seen a picture of Open Door Mountain from Antoinette Peak or who has actually seen the view in person has probably wondered if the traverse between the two, specifically on the north ridge of Open Door, goes without becoming a Class 5 matter necessitating ropes and climbing gear. It does, but working the ridges proper means Class 4 conditions with very loose rock and exposure. If you have issues with either of those, this is not a route for you. Otherwise, use this route to link two excellent Gros Ventre peaks and thereby make your day in the mountains longer and more enjoyable.
Note-- the spicy parts of Antoinette's south ridge can be bypassed on Class 2 ground to the west, and I am almost certain one can bypass the worst parts of Antoinette's north ridge by dropping from it to the west side as well (some Class 3 near the crest, and you will end up losing and regaining more elevation), but that means spending almost no time on the ridges' crests themselves, and I consider that to be a different route entirely. This page focuses on a true traverse of the ridges, and I was able to stay on the crests the whole time except for one spot on Open Door's north ridge where a rappel from a truly sketchy anchor situation down to a very iffy landing would have been necessary.
You can do this traverse in either direction. Since I went from Open Door to Antoinette, that is the way I will describe it. Depending on exactly how you ascend Antoinette as your first peak or descend it as your second, this route is 9-10 miles in all, with 5300-5500' of elevation gain. The traverse itself is only about a mile or a mile and a half. The saddle between the two peaks is a bit over 10,400'. Antoinette is 11,407', and Open Door is 11,113'.
About 11 miles southeast of Hoback Junction, look for a signed road heading north into the Granite Creek Recreation Area. This gravel-and-dirt road, which can be a little rough but is still passable for most passenger vehicles, follows Granite Creek for 10 miles to Granite Hot Springs, a popular spa (admission fee required). Along the way there are spectacular views of Granite Creek and the Gros Ventre Range.
7.5 miles up the road, look for a spur that makes a bridged crossing of Granite Creek. Turn here and follow signs for 0.1 mi to a trailhead. Find a spur road (usually closed) that makes a bridged crossing of Swift Creek. Just across the bridge, a sign indicates the beginning of Swift Creek Trail.
This page assumes you already have figured out how to get to the summit of Open Door or Antoinette. Since there are pages detailing the standard routes, I won't be redundant here. Both routes start from Swift Creek Trail. By the south face of Open Door, it is 2.5-3 miles and Class 2+ at the toughest; by the east ridge of Antoinette, it is 5 miles to the pass at the head of Swift Creek, all on trail, and then about a mile to the summit, no harder than Class 2 on that stretch.
From Open Door's summit, descend the loose, often-narrow ridge. The rock quality is poor. Nevertheless, a way keeps presenting itself until you finally reach some cliffs you can't downclimb. You may notice one or two gullies that are so steep they might be considered chimneys instead. I felt that I could have stemmed or chimneyed my way down them without needing a rope, but I decided to take a look around for something better. I'm glad I did, for after I did find a broken way down to the talus on the west side, and after I quickly got back on the ridge crest and looked back, I realized that those gullies either would have cliffed out on me or would have deposited me in a very precarious spot just feet away from even higher cliffs.
North Ridge of Open Door
Cross the saddle and start heading up Antoinette's south ridge. If you stay on the ridge, you will encounter one section of pleasant Class 3 scrambling that briefly turns into knife-edge, rotten Class 4. Pride and craziness made me stick with it, but there was some good pucker factor going on at one point.
Antoinette from the Antoinette-Open Door Saddle
After the scrambling section, the ridge broadens again and it is a Class 2 finish to the top.
Antoinette's South Ridge
Helmet and sticky shoes.
You might feel more comfortable having at least a 30m rope and gear to set rappel anchors, but good luck finding dependable rock.