Ulster is a province in the north of the island of Ireland. It is made up of nine counties, six of which are in Northern Ireland and three of which are in the Republic of Ireland. It is the second largest and second most populous of Ireland's four provinces, with Belfast being its biggest city. Unlike the other provinces, Ulster has a high percentage of Protestants, making up almost half of its population. English is the main language and Ulster English the main dialect. A minority also speak Irish, and there is a Gaeltacht in the west. Lough Neagh, in the east, is the largest lake in the British Isles, while Lough Erne in the west is one of its largest lake networks. The main mountain ranges are the Mournes, Sperrins, Croaghgorms and Derryveagh Mountains.