In some estuaries, a spectacular wave travels inland against the water flow on the highest tides. This natural wonder is a tidal bore and, of the hundred or so worldwide, about twenty occur in the UK.

This guide describes why tidal bores occur and ways to improve your chances of seeing one. Viewing tips are provided for ten featured tidal bores from Somerset to southwest Scotland and around the Wash and the Humber Estuary 

The best known is the Severn Bore in Gloucestershire but others include the Trent Aegir in Lincolnshire, the Nith Tidal Bore in Scotland, and the Dee Tidal Bore in Wales. Brief descriptions are also included for more than ten others that occur around the coast of the UK along with insights into how centuries of channel improvements for shipping may have affected the tidal bores in some estuaries.

The featured estuaries lie along some of the most beautiful and interesting stretches of coastline in the UK, which are well worth visiting on a day out. Brief suggestions for places to visit appear throughout the guide, including seaside resorts, nature reserves and tourist attractions, and popular destinations such as Gloucester, Cardiff, Chester, Liverpool, Ulverston, Carlisle, Dumfries, and Hull.

Less well-known sights include picturesque harbours, Roman ruins, sea cliffs, and places to go seal spotting or for a bird's eye view of the coast. These can all add to the experience on a trip to see a tidal bore, with the chance to learn more about the maritime history and wildlife of an estuary.