South Twin Sister is a prominent peak located in the Pacific Ranges mountain range of British Columbia, Canada. Rising to an elevation of approximately 2,251 meters (7,385 feet), it offers breathtaking panoramic views of the surrounding area. The mountain is known for its rugged and challenging terrain, making it a popular destination for mountaineers and outdoor enthusiasts.

During the winter season, South Twin Sister receives a significant amount of snowfall due to its high elevation. Snowpack ranges from an average of 3 to 5 meters (10 to 16 feet), creating ideal conditions for winter sports such as skiing and snowboarding. The mountain's snowpack also contributes to the water supply of nearby creeks and rivers during the spring and summer months.

One notable feature of South Twin Sister is its runoff, which feeds into the picturesque Twin Creek and eventually flows into the Chehalis River. This water source supports a diverse ecosystem and provides habitat for various wildlife species.

The name "South Twin Sister" is derived from its proximity to its sister peak, North Twin Sister, located just a few kilometers away. The origin of the name and any additional lore or legends associated with the mountain are not widely documented. However, the sheer beauty and challenging nature of South Twin Sister continue to attract adventurers seeking a thrilling mountaineering experience.