This shows the southwest slopes of the Big Sister which are home to the moderate scrambling route and was taken from the parking area off of the Smith-Dorrien Spray Lakes Road.
Big Sister is the highest peak in a well known group of mountains, the Three Sisters and I scrambled the Big Sister in June of 1993. The popular scrambling route heads up the forested ridge line on the left, then once at the treeline follows the NW ridge to the high point visible to the left of the pinnacle. From there you drop onto the NW slopes and then then follow them to gain the summit, which is not visible. Once at the treeline, continuing straight up the ridge is the harder alternative and looks quite steep (not as steep as it looks). The easier alternative is to find a "keyhole" chimney just above the treeline and go down that onto the low angled slabs and scree of the SW slopes proper. The downclimb onto the NW slope is more difficult scrambling and seems to stop many parties here as the sweeping NW slopes can be intimidating, especially if any snow lingers. The day we went up 2 parties were turned back here.
Uri (Trevor Urichuk) doing the classic pointer towards the final portion of the scramble on the NW face. This picture is from the middle of the crux pitch and from here you descend onto the face, then head upwards toward the right between the 2 lower snow bands. At the top of the lower snowband on the right, you cross over and ascend along the top of the upper snow band on the right if present. If not present, it would be on rock of course. From the top of that snowband you head straight up to the ridgeline and go left to the summit proper.
This picture was taken 1/3 of the way back up the crux pitch and gives a good profile of the crux pitch which provides access from the ridge onto the steeper NW face and it seems to deter some parties. It looks intimidating, but the rock is solid and the holds plentiful making for an excellent descent and ascent on the way back down. The Big Sister is a highly recommended scramble with virtually no approach which leaves you climbing as soon as soon as you leave your vehicle. It is a popular scramble, and the day we went up a party was just behind us and pushing fast. However, they almost turned back at the keyhole chimney you must descend to gain the W slopes, and from the summit we saw them at the top of the crux pitch, but they turned back.
This picture is important because this is the spot where some parties end up turning around. From this vantage the lower portion of the NW ridge looks very steep, and the actual route drops down the "keyhole" chimney to the SW slopes proper. The "keyhole" chimney is just ahead of the figures in the photograph. Many parties miss it and retreat as the ridge looks very steep. We went down the "keyhole" but descended down the ridge and found it was not that steep after all. If you are a confident scrambler the ridge poses no difficulties. Whether you tackle the ridge head on or drop onto the SW slopes, once you top out the ridge it is followed to the right to the high point where you must drop down onto the NW slopes.