Cuilcagh (from , meaning chalky peak) is a mountain on the border between County Fermanagh (in Northern Ireland) and County Cavan (in the Republic of Ireland). With a height of it is the highest point in both counties. It is also the 170th highest peak on the island of Ireland, and Ireland's only cross-border county top. Water from the southern slope flows underground until it emerges some miles away in the Shannon Pot, the traditional source of the River Shannon. The area is sometimes referred to as the Cuilcagh Mountains.