From the obvious trailhead at the south end of the road leading into Illecillewaet Campground, follow signage leading you 3 miles along a trail to Abbott Ridge, passing, among other things, the remnants of the century-old Glacier House and Marion Lake, along the way. Coming out of the forest, continue through subalpine meadows and eventually gain the north end of Abbott Ridge via the good trail. Here, the trail bends south and traverses the crest of Abbott Ridge for 1/4 mile or so before ending at a sign declaring the end of the trail.
From the end of the maintained trail, continue south along the crest, scrambling easily and following the many bits of use trail found here and there. Mount Abbott will be in the near distance at the south end of the ridge, with Mount Afton to its immediate west. The two peaks are separated by a snow and rock col.
Continue along Abbott Ridge, soon dropping down a short bit to a saddle between the ridge and Mount Abbott.
Easily surmounting Mount Abbott via class 2 scrambling up its north ridge, continue down Abbott’s west ridge (class 3), soon gaining the Abbott-Afton col.
From the col, simply follow Afton’s east buttress a few hundred feet up to the summit. Mostly class 2-3, I did encounter a 10-foot 4th class chimney 2/3 of the way up the buttress. I followed signs of prior use and obvious weaknesses until the minor difficulties mellowed out near the top.
A number of lines up the buttress are available.
To descend, either retrace your steps, or consider the alternate descent option described below.
Alternate Descent Option
From the summit, easily drop down the northwest ridge and head down. Although the going is only class 2, much of the ridge is loose and shifty.
At a point that seems right, leave the ridge and work west into the bowl between Mount Afton and Mount Abbott. Traverse the bowl, passing a small tarn along the way, and regain the obvious minor saddle connecting Abbott Ridge and Mount Abbott.
From the saddle, follow the crest of Abbott Ridge north until you find the trail again. Follow the trail back to the trailhead.
During typical summer conditions, normal hiking gear should be sufficient. Crampons/axe may be needed if snow is present. In late July 2007, I was able to cross a couple of minor snowfields along the route with only trekking poles.