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A Trip Down the Thames

Updated: Aug 30, 2023

by Stephen Andrews

The Thames is probably one of the best-known rivers in the world. If you live in London, you’ll probably be familiar with the part that flows through the city, but do you know just how big it actually is? In fact, it stretches an amazing 346 kilometres from Gloucestershire to the west, through the centre of London, then east until it finally reaches the North Sea in Essex. It’s the longest river in England and the second-longest in the UK after the River Severn in Wales. How deep is it? Well, the river’s depth varies wildly but at Westminster Bridge it has been recorded as 1.9 metres.

I love walking by the Thames or taking a boat trip from Westminster to Greenwich … there’s lots to discover as the majestic Thames flows through the countryside, the city and the centuries.

The journey begins …

The source of the Thames is at a place called Thames Head near the town of Cirencester, in the Cotswolds, west of London. There’s hardly anything to see there, except some rocks and a trickle of water. But, within a couple of miles, the river starts to grow. At Lechlade-on-Thames, a few miles away from its source, it measures 18 metres, but by the time it reaches the sea in Essex to the east of London, it’s 28 kilometres across.

Touring the Thames

From Gloucestershire, the river soon reaches Oxford, where it’s now roughly 46 metres wide. Here, in summer, the river is alive with people enjoying cruises in elegant flat-bottomed boats called punts. Narrowboats, a small riverboat, can also be seen making their way from the north of England on the Oxford Canal. As it makes its way towards London it passes through a town called Pangbourne where the author Kenneth Grahame wrote the famous children’s book ‘The Wind in the Willows’. Inspired by the Thames, it features characters like Toad and Ratty who love ‘messing about on the river.’

The river then flows through Henley-on-Thames famous for its annual rowing regatta celebration, then east again, passing Eton College, the famous boy’s school, and Windsor Castle.

At Teddington, where it’s now 76 metres wide, the Thames is tidal which means its level rises and falls twice daily with the tides of the North Sea. Depending on the time of year, the river rises and falls twice a day by anything up to 7 metres. Then, passing through Hammersmith and Wandsworth, it flows on through central London where it’s roughly 229 metres wide and then continues east past Greenwich and the Isle of Dogs. When it reaches Gravesend, the river has widened to 730 metres and turns into what is called the Thames Estuary as it flows, finally, into the sea.


In the 18th century, as London became the centre of the British Empire, the river was one of the world's busiest waterways. Over the next century the docks expanded to the Isle of Dogs in the East End and beyond. But the growth of road transport and the decline of the Empire in the years following the end of the World War I in 1918 reduced the economic importance of the river.

By the 1970s the docks and warehouses along the riverside in central London had fallen into disrepair. From then on, the Port of London Authority concentrated cargo-handling at Tilbury, 32 kilometres downstream of the city. When I first came to London in the 1980s, the old warehouses along the river near Tower Bridge were still derelict and vacant. A few years later they became ‘gentrified’ and transformed into the expensive apartments and office buildings of today.

Famous bridges

How many bridges span the Thames?

More than you might think! A total of 104 bridges cross over the Thames, 75 bridges going west from Teddington to its source, and 29 bridges going east from Teddington, through central London.

These include Blackfriars, Waterloo, Westminster, Battersea, Hammersmith and Chiswick. Of these, the Millenium Bridge near St Paul’s is the only bridge across the Thames that is solely for pedestrians.

The two most famous are of course Tower Bridge and London Bridge.

Tower Bridge

Tower Bridge, and the nearby Tower of London, is a major tourist attraction. Many people think it’s very old, but it was actually built in 1894 by the Victorians. It’s about 240 metres in length and provides an opening 76 metres wide. Its two towers rise 61 metres above the river. Between the towers stretch a pair of glass-covered walkways designed to allow pedestrians to cross even when the bridge is raised.

London Bridge

You might have heard the famous song: ‘London Bridge is falling down, falling down...’ a popular nursery rhyme sung by children. And actually the bridge has fallen down several times throughout its history! In Roman times, the bridge was wooden and when they left London, it rotted away. Following the Norman Conquest in 1066, King William rebuilt the bridge. It was then destroyed by fire in 1136. Hard to believe now, but from the 14th to 17th centuries, houses and shops were built on the bridge and it became one of the most popular shopping areas in London. The number of houses on the bridge reached its maximum in the late 14th century, when there were 140! Demolition of the houses was only completed in 1761. The current London Bridge was constructed from 1967 to 1972 and opened by the Queen on 17th March 1973. The bridge more recently had new security barriers installed following the terrorist attacks of 2017 and 2019. A bridge with an amazing story!

Walking under water

If you fancy walking underneath the river, there are also two foot-tunnels, one at Greenwich and the other at Woolwich, as well as a number of road and rail tunnels. Or you can catch the Woolwich Ferry linking Woolwich in the borough of Greenwich with North Woolwich in Newham. The latest way of getting across the river is by 'The Emirates Air Line', a cable-car that crosses the Thames in East London, between The Royal Docks at Canning Town and the Greenwich Peninsula.

Famous landmarks

You’ve probably seen or ridden on the London Eye, a sort of enormous Ferris wheel on the South Bank. It’s close to the famous Royal Festival and Queen Elizabeth halls, two of the biggest concert venues in London. Other outstanding riverside landmarks you can see on a boat voyage through London include Kew Gardens, the Houses of Parliament, the Tate Modern and Tate Britain art galleries, St. Paul’s Cathedral, the Tower of London, Tower Bridge, the Canary Wharf financial centre and, at Greenwich, the former Royal Naval College as well as the Millenium Dome, a major exhibition and concert venue. Downriver even further, you’ll discover the futuristic-looking Thames Barrier.

The Thames Barrier

As I’ve said, the Thames is a tidal river, which means that its level rises and falls with the tides of the sea. Potentially, this means that the centre of London could easily be flooded. In fact, there was a huge flood in 1928, fourteen people died and thousands were made homeless when floodwaters poured over the top of the Embankment.

To prevent this happening again, in 1980, the gleaming steel Thames Barrier was built near Woolwich. It spans 520 metres across the river and protects central London from flooding caused by tidal surges. The Barrier has 10 steel gates that can be raised into position across the Thames. When raised, the main gates stand as high as a 5 storey building and as wide as the opening of Tower Bridge. Each main gate weighs 3,300 tonnes. Shigeri used to be able to see the Thames Barrier from the window of the flat she lived in a few years ago.

Islands floating in the river

Eel Pie Island sits in the River Thames at Twickenham in the Borough of Richmond. It’s accessible by boat or from the left (north) bank by footbridge.

Travelling east into Essex, you’ll find Canvey Island, a small island in the Thames Estuary, separated by creeks (small rivers) from the Thames. There are great views across the Thames and it’s an ideal spot for watching London-bound ships come and go.

Almost opposite Canvey Island, again in the Thames Estuary, but on the southern Kent coast, sits the Isle of Sheppey. Called Kent's ‘Treasure Island’, Sheppey offers sandy beaches, beautiful marshes and bird reserves.


The river has rather a dirty history! As early as the 1300s, the Thames was used to dispose of waste matter produced in the city of London, turning the river into an open sewer. Over the years, pollution has been so bad that it was declared biologically dead in 1950, although happily these days it’s one of the cleanest in the world and a huge variety of wildlife has returned to live in the river.

Now, the Thames supports more than 115 species of fish, including seahorses and sharks, and 92 species of birds. The most recent count revealed there were about 900 harbour seals and 3,200 grey seals downriver in the Thames Estuary.

Back in 2006, a whale was actually spotted in the river. Affectionately nicknamed Willy by Londoners, she was a juvenile female bottlenose whale, measuring 5 metres long and weighing about 12 tonnes. The whale appeared to have been lost, as her normal habitat would have been around the coasts of the far north of Scotland and the seas around the Arctic Ocean. It was the first time the species had been seen in the Thames since records began in 1913. Sadly, she died as she was being rescued.

Fun and games on the river

In earlier centuries, London winters were often so severe that the Thames would freeze solid. The ice was so thick that ‘Frost Fairs’ would be held on the river itself. People enjoyed shopping, horse racing, ice-skating, football, ninepin bowling and sledding all in the middle of the river! The last time this happened was in February 1814, not that long ago. Sounds like fun! Pity that with Global Warming, we won’t see that happening ever again…

When the river’s level falls, small, sandy beaches appear at its sides. In the past, these were very popular with Londoners who used them to sunbathe in summer. There’s quite a big one near Blackfriars Bridge where people still hang out today. The river is also popular with beachcombers who use metal-detectors to see if they can find any hidden treasure washed up from the river.

Rowing and sailing clubs are common along the Thames and people Kayak and canoe. Major annual events include the Henley Royal Regatta, where boats of all shapes and sizes take sail, and the Boat Race, an annual rowing contest between crews from Oxford and Cambridge universities. The Thames has even been used during two Summer Olympic Games, in 1908 for rowing and 1948 for rowing and canoeing.

I hope you’ve enjoyed this quick trip down the Thames and found it interesting, even if you don’t live in London. If you do, with sunny spring weather on the way, it’s the perfect time to start messing about on the river …





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