Indian Man Lake Nature Reserve was designated in 1990 to protect a mature red oak forest near Lower Caledonia, Guysborough County. This forest type is rare in eastern Nova Scotia.

The reserve was expanded in 2015 to include riparian habitat and shrub swamps along tributaries of West River St. Marys. These habitats are frequented by wood turtles – a listed species at risk. The associated, hummocky terrain primarily supports dense forest of black spruce, white pine, balsam fir and tamarack.

A natural gas pipeline corridor passes between the two portions of the nature reserve. It is not part of the reserve.