tidal bore waves

Tidal bore waves are formed in a small number of ocean-connected rivers worldwide, and take shape when a higher-than-average tide funnels through a rivermouth into a narrowing inland passage. The best-known surfing tidal bores are found in Britain's Severn River, the Amazon in Brazil, and the Dordogne River in France. Equinox tides generally produce the biggest bore surges, and a breaking bore wav...