A wetland area of central Somerset between the Quantock and Mendip hills, consisting of moors formed from a submerged and reclaimed landscape. Prone to regular flooding, particularly before the sea defences were enhanced at Bridgewater in the early 20th century. The area broadly corresponds to the administrative district of Sedgemoor.
Much of the area is at, or only slightly above, sea level, so until it was drained in the 17th century it was a marsh that was frequently flooded by the sea. The area was settled by the Bronze Age, with the population living on artificial islands connected by wooden causeways on wooden piles, supporting themselves largely by hunting and fishing in the surrounding marsh. Several towns were also built on the natural 'islands' of slightly raised land, including Brent Knoll, Glastonbury, and the low range of the Polden Hills. It's easy to see why the area aquired a number of legends, particularly of King Arthur and his knights, who may have based his court at the hill fort at Cadbury.
Although now mechanically drained by a network of drainage channels, known locally as "rhynes" (pronounced "reens"), the levels are not as intensively drained or farmed as the East Anglian fens (historically a similar area of low marsh), and are still liable to flooding in winter. Consequently the Levels retain a rich biodiversity and contain several Sites of Special Scientific Interest. The "Somerset Levels and Moors" is also a recognised Environmentally Sensitive Area.