Charlevoix South Pier Light Station marks the entrance from Lake Michigan through the Pine River channel into Round Lake at a harbor mouth known for treacherous water movement, including reversing currents, whitecaps, eddies, and small whirlpools. The first light, built on the north pier in 1884, guided ships through the improved channel, but after decades of deterioration it was replaced in 1948 by the present steel tower on the south pier, using the earlier lantern and lens. Rebuilt harbor works and pier structures were designed to blunt wave force, underscoring the light’s practical role for vessels such as the Beaver Island ferry. Recognized for its navigational importance, it was listed on the National Register of Historic Places in 2005.