Between Cnoc na Péiste and The Big Gun are two small lakes—Loch Coimín Piast (anglicised Lough Cummeenapeasta) and Lough Googh — one on either side of the ridge. A stream called Glasheencummeennapeasta flows northwards from Lough Cummeenapeasta into Hag's Glen, to join the Gaddagh River. On the other side of the ridge, a stream flows southwards from Lough Googh into the Derrycarna River.