tmôr yr afon the river sea dating from the 3800s BC. The Levels were the location of the Glastonbury Lake Village as well as two Lake villages at Meare Lake. Several settlements and hill forts were built on the natural "islands" of slightly raised land, including Brent Knoll and Glastonbury.

The city of Swansea is the largest settlement on the Welsh coast of the Bristol Channel. Other major built-up areas include Barry (including Barry Island), Port Talbot and Llanelli. Smaller resort towns include Porthcawl, Mumbles, Saundersfoot and Tenby. The cities of Cardiff and Newport adjoin the Severn estuary, but lie upstream of the Bristol Channel itself. On the English side, the resort towns of Weston-super-Mare, Burnham-on-Sea, Watchet, Minehead and Ilfracombe are located on the Bristol Channel. Barnstaple and Bideford are sited on estuaries opening onto Bideford Bay, at the westernmost end of the Bristol Channel. Just upstream of the official eastern limit of the Channel, adjoining the Severn estuary, is the city of Bristol, originally established on the River Avon but now with docks on the Severn estuary, which is one of the most important ports in Britain. It gives its name to the Channel, which forms its seaward approach. Bristol Channel floods, 1607
On 30 January 1607 (New style) thousands of people were drowned, houses and villages swept away, farmland inundated and flocks destroyed when a flood hit the shores of the Channel. The devastation was particularly bad on the Welsh side, from Laugharne in Carmarthenshire to above Chepstow on the English border. Cardiff was the most badly affected town. There remain plaques up to 8 ft (2.4 m) above sea level to show how high the waters rose on the sides of the surviving churches. It was commemorated in a contemporary pamphlet "God's warning to the people of England by the great overflowing of the waters or floods."