London is one of the most iconic cities in the world and the river Thames has always been an important part of its history. In this article, discover 10 facts about the River Thames that you may not have heard before.

Fascinating river Thames facts


It's a really long river

At 215 miles (346km) long, the River Thames is the second longest river in the UK (after the river Severn) – it even has 45 different locks and over 180 islands, including large, lush marshlands and tiny islets!

It starts in Gloucestershire

Most people think the river Thames runs solely through London, but believe it or not, the river actually starts in Gloucestershire. The Thames runs through nine different counties (including Greater London) and ends at the Thames Estuary which leads into the North Sea.  

It's not as wide as you think

The mouth (end) of the River Thames is around 18 miles (28.9km) wide, but surprisingly, in some areas the width of the river can be as small as 18 meters (which is still quite wide)!

Part of the river is tidal

The Thames has tidal and non-tidal sections; the non-tidal portion runs from Gloucestershire to the first lock on the river Teddington and the tidal section (99 miles or 160km) stretches from the Teddington lock all the way to the Thames Estuary where the river meets the North Sea. 

Venus Clipper and Westminster
Thomas Wyke Thames Frost Fair

It can freeze over!

Believe it or not, the River Thames can completely freeze over – although it hasn’t done so for a very long time. The ice was thick enough to walk on, so people used to ice skate on the river and host frost fairs. This impromptu tradition took place between the early 1600s and early 1800s, featuring a variety of food, drinks, and trade stands. During the last Frost Fair in 1814 an elephant was marched across the river alongside Blackfriars Bridge!

Last winter, Bankside travelled back in time and celebrated this extraordinary event with a multimedia trail of street art murals, digital art installations and events. Check out Bankside Frost Fair.

The Thames influenced some famous London delicacies

A range of fresh and saltwater fish are harvested from the river Thames, including eels, which led to London’s famous Pie and Mash shops creating and selling dishes like jellied eels.

There are lots of bridges

For a long time, London Bridge was the only bridge where you could cross the river Thames, but nowadays the Thames has over 200 bridges.  There are 21 bridges in central London between Hammersmith Bridge and Tower Bridge.

Launched in 2019 the Illuminated River project transformed the capital at night, bathing 9 of the bridges that cross the Thames in environmentally-friendly LED light. You can get up close and sail underneath the world’s longest piece of public art by joining an Illuminated River Official Boat Tour.

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Londoners drink from the Thames

Chances are if you live in London, you’ve probably drank water from the Thames. Around two-thirds of London’s drinking water supply comes directly from the river Thames – after it’s been filtered and treated of course!

Tonnes of wildlife

The Thames was once one of the most polluted rivers in the country and was declared biologically dead. But after decades of changes and hard work to clean the river, it’s now home to 115 different fish species, as well as seals, dolphins and a variety of birds.

Once upon a time, it was a polar bear’s swimming pool

Back when King Henry VIII was ruling, he was gifted a polar bear by the King of Norway. The polar bear was kept at the zoo in the Tower of London, but on hot days it was allowed to swim in the river Thames.

Plan your next trip to the iconic river

Now that you’ve read these interesting facts about the river Thames, why not go and see it for yourself? Uber Boat by Thames Clippers is the perfect way to get across London, taking you down the River Thames and letting you see the iconic skyline up close.

Plan your journey today