Below Teddington Lock (about 55 miles/89 kilometres upstream of the Thames Estuary) the river is subject to tidal activity from the North Sea. Before the lock was installed the river was tidal as far as Staines. London, capital of Roman Britain was established on two hills, now known as Cornhill and Ludgate Hill. These provided a firm base for a trading centre at the lowest possible point on the Thames. A river crossing was built at the site of London Bridge. London Bridge is now used as the basis for published tide tables giving the times of high tide. High tide reaches Putney about 30 minutes later than London Bridge, and Teddington about an hour later. The tidal stretch of the river is known as "the Tideway".
The principal tributaries on the Tideway include the rivers Brent, Wandle, Effra, Westbourne, Fleet, Ravensbourne (the final part of which is called Deptford Creek), Lea, Roding, Darent and Ingrebourne. At London, the water is slightly brackish with sea salt, being a mix of sea and fresh water.
This part of the river is managed by the Port of London Authority. The flood threat here comes from high tides and strong winds from the North Sea, and the Thames Barrier was built in the 1980’s to protect London from this risk.
The average discharge of the Thames grows up to approximately 66 cubic metres per second at the end of its non-tidal section, at Kingston upon Thames, a figure which is exceeded by some other British rivers (e.g., the Severn and the Tay). Indeed, if the were not a tidal river, its average discharge in the centre of London would be somewhere between 80 and 100 cubic metres per second, and the Thames would look like a small river, not the large river we can see today by Westminster, the Houses of Parliament or the City.
The river Thames contains over 80 islands ranging from the large esturial marshlands of the Isle of Sheppey, Isle of Grain and Canvey Island to small tree covered islets like Rose Isle, Oxfordshire and Headpile Eyot Berkshire. Some of the largest inland islands - Formosa Island near Cookham and Andersey Island at Abingdon - were created naturally when the course of the river divided into separate streams, while Desborough Island, Ham Island at Old Windsor and Penton Hook Island were artificially created by lock cuts and navigation channels. Chiswick Eyot is a familiar landmark on the Boat Race course, while Glover's Island forms the centrepiece of the spectacular view from Richmond Hill. Islands with a historical interest are Magna Carta Island at Runnymede, Fry's Island at Reading and Pharaoh's Island near Shepperton. In more recent times Platts Eyot at Hampton was the place where MTBs were built, Tagg's Island near Molesey was associated with the impresario Fred Karno, and Eel Pie Island at Twickenham was the birthplace of the South East’s R&B music scene.
The Water Music composed by George Frideric Handel premiered in the summer of 1717 (July 17, 1717) when King George I requested a concert on the River Thames. The concert was performed for King George I on his barge and he is said to have enjoyed it so much that he ordered the 50 exhausted musicians to play the suites three times on the trip.
The Sex Pistols played a concert on the Queen Elizabeth Riverboat on June 7, 1977, the Queen's Silver Jubilee year, while sailing down the river.
"Waterloo Sunset" is a song released as a single by The Kinks in 1967, and featured on their album Something Else by the Kinks. It was composed and produced by The Kinks lead singer and songwriter Ray Davies and is one of the band's best known and most acclaimed songs. The lyrics are from the point of view of a solitary man on the south bank of the Thames watching (or imagining) the romantic encounters of a couple at Waterloo Underground, then crossing Waterloo Bridge.