The term LOUGH ERNE (4 letters) is an Irish lake located in County Fermanagh, Northern Ireland. It is the second-largest lake system in Northern Ireland and the sixth-largest in the British Isles. The lake is fed by the River ERNE, which flows into the Atlantic Ocean. The term LOUGH REE (3 letters) is an Irish lake located in County Roscommon, Ireland. It is the second-largest lake in the Republic of Ireland and the fourth-largest in the British Isles. The lake is fed by the River Shannon, which flows into the Atlantic Ocean. Both lakes are popular tourist destinations, offering activities such as fishing, boating, and bird watching.