How far away is the mountain that is highest among Mourne Mountains from the Irish Sea?
Mourne Mountains:  It includes the highest mountains in Northern Ireland and the province of Ulster. Mourne Mountains:  The highest of these is Slieve Donard at 850 m . Slieve Donard:  Slieve Donard sits near the town of Newcastle on the eastern coast of County Down, only 2 miles (3 km) from the Irish Sea.
i don't know