Tidal bores

river in Papua New Guinea and Indonesia

water wave traveling upstream a river or narrow bay due to incoming tide

river in Aberdeenshire, Scotland, UK, flows into the North Sea at Aberdeen

river in western Zhejiang, China

river in Maranhão, Brazil

thumb|Pororoca near the mouth of the Araguari River (Amapá)|Araguari River, seen from an airplane The Pororoca (, ) is a tidal bore, with waves up to high that travel as much as inland upstream on the Amazon River and adjacent rivers. It occurs at the mouth of the river where its waters meet the Atlantic Ocean. It can be observed from the islands Marajó and Caviana, and in various rivers of the state Pará.

river in New Brunswick, Canada

tidal bore seen on the tidal reaches of the River Severn in south western England