Ponkapag Pond is a 203-acre impoundment is located on the border of Canton and Randolph, Massachusetts about a half mile south of Route 128 and a half mile east of Route 138. It has a maximum depth of seven feet and an average depth of four feet. As would be expected on a pond this shallow, aquatic vegetation is pervasive and very abundant. Only a small portion of the eastern shoreline is developed; the southeastern and western shores are bordered by large expanses of marshland. There is no formal public access, but there is street-side parking and a place to launch cartop boats and canoes at the spillway on the pond's western tip.