The coastline is composed mainly of resistant rocks that give rise in many places to tall cliffs.
Cornwall has a border with only one other county, Devon, which is formed almost entirely by the River Tamar, and the remainder (to the north) by the Marsland Valley.
Beaches on the south coast usually consist of coarser sand and shingle, interspersed with rocky sections of wave-cut platform.
There are two river estuaries on the north coast: Hayle Estuary and the estuary of the River Camel, which provides Padstow and Rock with a safe harbour.
The seaside town of Newlyn is a popular holiday destination, as it is one of the last remaining traditional Cornish fishing ports, with views reaching over Mount's Bay.
Extensive stretches of Cornwall's coastline, and Bodmin Moor, are protected as an Area of Outstanding Natural Beauty. It is regarded as the county flag by Cornwall Council.
The banner of Saint Piran is a white cross on a black background (in terms of heraldry 'sable, a cross argent').