<P> The River Thames ( / tɛmz / ( listen ) TEMZ ) is a river that flows through southern England , most notably through London . At 215 miles ( 346 km ) , it is the longest river entirely in England and the second longest in the United Kingdom , after the River Severn . It also flows through Oxford ( where it is called Isis ) , Reading , Henley - on - Thames and Windsor . The lower reaches of the river are called the Tideway , derived from its long tidal reach up to Teddington Lock . It rises at Thames Head in Gloucestershire , and flows into the North Sea via the Thames Estuary . The Thames drains the whole of Greater London . </P>
<P> The River Thames ( / tɛmz / ( listen ) TEMZ ) is a river that flows through southern England , most notably through London . At 215 miles ( 346 km ) , it is the longest river entirely in England and the second longest in the United Kingdom , after the River Severn . It also flows through Oxford ( where it is called Isis ) , Reading , Henley - on - Thames and Windsor . The lower reaches of the river are called the Tideway , derived from its long tidal reach up to Teddington Lock . It rises at Thames Head in Gloucestershire , and flows into the North Sea via the Thames Estuary . The Thames drains the whole of Greater London . </P>
where does the river thames stop being tidal
where does the river thames stop being tidal
Teddington Lock
Teddington Lock