County Cavan shares a border with County Fermanagh in Northern Ireland. The county town is Cavan Town. Other important towns are Bailieborough, Belturbet, Ballyjamesduff, Virginia, Granard and Killeshandra.

Cavan is predominantly hilly county except that it also contains part of the low-lying lakes of Lough Oughter (165 km2) and Upper Lough Erne (110km2).

The county contains part of the drumlin belt of northern Ireland. The county is rich in lakes, especially in the west where Loughs are also known as “lakes” in Irish. Of these lakes, six are major with a area more than 80 km²: Lough Gowna (140 km²), Lough Sheelin (76 km²), Lough Ramor (86 km²), Lough MacNean (67 km²), Drumcagh Lake or Glenco(60km²) and Kings Lake or Cronk(60km²). Cavan is one of only two counties in Ireland without a significant lake.