The Shannon Estuary (Irish: Inbhear na Sionainne) is a large estuary where the River Shannon flows into the Atlantic Ocean. The estuary has Limerick at its head and its seaward limits are marked by Loop Head to the north and Kerry Head to the south. The estuary defines the main boundary between County Kerry/County Limerick to the south and County Clare to the north. The length of the Shannon Estuary is 97 km (60.27 mls).