The River Severn (Welsh: Afon Hafren) Photos from source to mouth The River Severn, like all rivers, provide us with food, energy, recreation, transportation routes, and water for irrigation and for drinking. Join Winnie the Pooh and friends as they journey down the River Severn from source to sea and discover exciting facts and information about the river. Introduction to the River Severn The River Severn seeps out of the earth in a peat bog in the Cambrian Mountains of Wales. Pooh and friends at the source of the Severn Facts about the Source of the River Severn peat bog location Plynlimon, Cambrian Mountains, Wales elevation 610 m (2,001 ft) coordinates 52.493465°N 3.734578°W Two hundred and twenty miles (354km) and four counties later, it is swallowed by the Bristol Channel and eventually the Atlantic Ocean. The friends are amazed at the enormous size of the mouth of the River Severn Facts about the Mouth of the River Severn location Bristol Channel, England elevation 0 m (0 ft) size over five miles wide The River Severn is 6 miles (10 km) longer than the River Thames, making it the longest river in Great Britain. It flows in a semi-circular route through the Welsh county of Powys and the English counties of Shropshire, Worcestershire and Gloucestershire. Interesting River Severn facts As well as the River Severn, two other rivers have their source on the mountain - the rivers Wye and Rheidol. The Severn's name is derived from the Latin word Sabrina, previously "Hafren" in Welsh, which means "boundary". The Hafren Forest takes its name from the River Severn, the Afon Hafren in Welsh The estuary of the River Severn is over five miles wide. The estuary forms a physical boundary between England and Wales. During high tides a wall of water can travel upstream for over 25 miles. This tidal wave is known as the Severn Bore and can swell the depth of the river by up to 50ft (15m). .