Where is the main source of the River Shannon in Ireland?

Question

I think it may be in Upper Lough Erne, Co Cavan, close to the border with NI, but I do not know for certain. I know that the Shannon has many tributaries which drain a large area of the central part of Ireland, this Q is about its main stream.

Answer 1

I think it's called the Shannon Pot. Did you try wikipedia for more information?