The  River Severn  is the longest river in Britain, running from the Welsh mountains, down through the countryside and county town of Gloucester, to the flatlands of the Severn Estuary. The river becomes tidal just north of Gloucester.

The fast flowing silty water and mud flats of the Severn Estuary attract large populations of birds and fish, including waterfowl, ducks and geese. Some birdlife, such as Bewick’s Swans, White-fronted Geese and Ringed Plovers, migrate thousands of miles around the globe, stopping to feed here each year. Large numbers of Atlantic salmon and sea trout also pass through the estuary in both directions, migrating each year into its tributary rivers.

The Severn Estuary has one of the highest tidal ranges in the world - about 15 metres. During the highest tides, rising water is funneled up the estuary into a wave that travels rapidly upstream against the river current. Local surfing enthusiasts enjoy the thrill of trying to surf this tidal bore which can be as high as 2 metres!