• Many times a year, the high Spring tide forms a wave that surges up the River Severn as a wall of water.
  
  
• As the bore passes, the depth of water in the river instantly rises and may flood the bank.
  
  
• The flow of the river is reversed and remains so until the tide begins to ebb.
  
  
• The height of the bore depends on a number of factors but the most important is the tidal range.
  
  
• Depending on the depth of water, the bore may be a smooth wave or have a breaking crest.
  
  
• The wall of a large bore may be 2 metres high and travel at some 14 knots.
  
  

There are numerous viewing points on the river bank anywhere north of about Newnham. The most popular sites, with easy access from roads are at Over Bridge, Minsterworth and Stonebench. Stonebench is also within walking distance of the Sharpness canal. If a large Severn bore is predicted there will be many hundreds of visitors.

A remarkable photo of surfers riding the Severn bore in April 2007. It was taken from a microlight aircraft by Mark Humpage. The photograph shows that a series of waves, rather than a single wave, may constitute a bore. Note that in the shallow water near the shore, the waves collapse and break The largest wave of this bore was just over a metre in height.
	Modified from a photo by Mark Humpage   (c) mhWeather

A small bore wave surging up the River Severn.  For scale note the rigid inflatable on the tidal side. Picture taken from the bank at Stonebench where the river channel is narrow. The bore wave is interrupted by weirs near Gloucester but the effects of the bore continue upto Tewkesbury.

Remember, as the bore passes it will often break violently along the bankside; the river level will instantly rise and will often flood the adjacent area.

Visitors should choose their viewing point with care.

Disclaimer: All linked sites are believed to be in the public domain. They are verified regularly but the Severn-boating page accepts no reponsibility for the nature or accuracy of information on those sites.