With its waters varying from freshwater to almost seawater, the Thames supports a variety of wildlife and has a number of adjoining Sites of Special Scientific Interest, with the largest being in the North Kent Marshes and covering 20.4 sq mi (5,289 ha).

Sculptures titled Tamesis and Isis by Anne Seymour Damer are located on the bridge at Henley-on-Thames, Oxfordshire (the original terracotta and plaster models were exhibited at the Royal Academy, London, in 1785.

But centuries of human intervention have transformed it into a deep tidal canal flowing between 200 miles of solid walls; these defend a floodplain where 1.5 million people work and live.

Below the barrier, the river passes Woolwich, Thamesmead, Dagenham, Erith, Purfleet, Dartford, West Thurrock, Northfleet, Tilbury and Gravesend before entering the Thames Estuary near Southend-on-Sea.

[22][23] Sediment cores up to 10 m deep collected by the British Geological Survey from the banks of the tidal River Thames contain geochemical information and fossils which provide a 10,000-year record of sea-level change.

This is the usual tidal limit; however, high spring tides can raise the head water level in the reach above Teddington and can occasionally reverse the river flow for a short time.

Researchers have identified the River Thames as a discrete drainage line flowing as early as 58 million years ago, in the Thanetian stage of the late Palaeocene epoch.

[36] Until around 500,000 years ago, the Thames flowed on its existing course through what is now Oxfordshire, before turning to the north-east through Hertfordshire and East Anglia and reaching the North Sea near present-day Ipswich.

[42] At the height of the last ice age, around 20,000 BC, Britain was connected to mainland Europe by a large expanse of land known as Doggerland in the southern North Sea Basin.

[43] Since Roman times and perhaps earlier, the isostatic rebound from the weight of previous ice sheets, and its interplay with the eustatic change in sea level, have resulted in the old valley of the River Brent, together with that of the Thames, silting up again.

Crowds gathered along the riverbanks to witness the spectacle but there was soon concern, as the animal came within yards of the banks, almost beaching, and crashed into an empty boat causing slight bleeding.

[50] The British Museum has a decorated bowl (3300–2700 BC), found in the river at Hedsor, Buckinghamshire, and a considerable amount of material was discovered during the excavations of Dorney Lake.

Starting in AD 43, under the Emperor Claudius, the Romans occupied England and, recognising the river's strategic and economic importance, built fortifications along the Thames valley including a major camp at Dorchester.

Cornhill and Ludgate Hill provided a defensible site near a point on the river both deep enough for the era's ships and narrow enough to be bridged; Londinium (London) grew up around the Walbrook on the north bank around the year 47.

Economic prosperity and the foundation of wealthy monasteries by the Anglo-Saxons attracted unwelcome visitors and by around AD 870 the Vikings were sweeping up the Thames on the tide and creating havoc as in their destruction of Chertsey Abbey.

According to historian Peter Ackroyd, "a public lavatory on London Bridge showered its contents directly onto the river below, and latrines were built over all the tributaries that issued into the Thames.

[56] During a series of cold winters the Thames froze over above London Bridge: in the first Frost Fair in 1607, a tent city was set up on the river, along with a number of amusements, including ice bowling.

[63] There followed a concerted effort to contain the city's sewage by constructing massive sewer systems on the north and south river embankments, under the supervision of engineer Joseph Bazalgette.

[64] The decline of heavy industry and tanneries, reduced use of oil-pollutants and improved sewage treatment have led to much better water quality compared to the late 19th and early- to mid-20th centuries and aquatic life has returned to its formerly 'dead' stretches.

In the past, commercial activities on the Thames included fishing (particularly eel trapping), coppicing willows and osiers which provided wood and baskets, and the operation of watermills for flour and paper production and metal beating.

[71] As a result of the Marchioness disaster in 1989 when 51 people died, the Government asked the Maritime and Coastguard Agency, the Port of London Authority and the Royal National Lifeboat Institution (RNLI) to work together to set up a dedicated Search and Rescue service for the tidal River Thames.

The Environment Agency has patrol boats (named after tributaries of the Thames) and can enforce the limit strictly since river traffic usually has to pass through a lock at some stage.

Upstream of Wandsworth Bridge a speed limit of 8 kn (15 km/h) is in force for powered craft to protect the riverbank environment and to provide safe conditions for rowers and other river users.

[93] The majority of sediment cores show a clear decrease in Hg concentrations close to the surface, which is attributed to an overall reduction in polluting activities as well as improved effectiveness of recent environmental legalisation and river management (e.g. Oslo-Paris convention).

Two rowing events on the River Thames are traditionally part of the wider English sporting calendar: The University Boat Race (between Oxford and Cambridge) takes place in late March or early April, on the Championship Course from Putney to Mortlake in the west of London.

In 2006, British swimmer and environmental campaigner Lewis Pugh became the first person to swim the full length of the Thames from outside Kemble to Southend-on-Sea to draw attention to the severe drought in England which saw record temperatures indicative of a degree of global warming.

It begins with a scavenger and his daughter pulling a dead man from the river near London Bridge, to salvage what the body might have in its pockets, and leads to its conclusion with the deaths of the villains drowned in Plashwater Lock upstream.

It starts as a tale of anthropomorphic characters "simply messing about in boats" but develops into a more complex story combining elements of mysticism with adventure and reflection on Edwardian society.

In poetry, William Wordsworth's sonnet On Westminster Bridge closes with the lines: T. S. Eliot makes several references to the Thames in The Fire Sermon, Section III of The Waste Land.

The floods were caused by 4.6 in (120 mm) of rainfall (including snow); the peak flow was 61.7×10^9 L (13.6×10^9 imp gal) of water per day and the damage cost a total of £12 million to repair.