27 Fascinating River Thames Facts to Know Before You Visit London

As you begin planning your London trip and study maps of the city, you probably spotted it right away: the River Thames cuts through the heart of the city – and is in fact the reason that London exists in this spot at all!

Whether you decide to take a Thames river cruise on your London trip or just walk along its banks while admiring the other attractions you can see there (Tower Bridge! Parliament! The London Eye, oh my!), it’s natural to be curious about this important waterway. Below you’ll find a list of River Thames facts that cover the basics, the bizarre, and everything in between.

As with many important cities across the globe, the presence of the River Thames – which looks little like it did back with neolithic humans lived on its banks or Romans settled here 2,000 years ago – has been an important aspect of the city all along. From transport to trade to tourism, the Thames carries the lifeblood through the city from its origins in the west to its end in the east.

Ready to smarten yourself up about London’s most significant natural feature?

Interesting facts about the River Thames 

To kick off this list of River Thames facts, let’s check out some dimensions and other details.

1. The Thames is the longest river in England – The Thames is 215 miles (346km) long. Its source can be found at Thames Head in the Cotswolds, whilst its mouth is at Southend on Sea. Here the river meets with the North Sea, which ironically is in the south of England!  The Thames has two parts; the tidal and the nontidal. 
2. The Thames is the second-longest river in the U.K. – The 220-mile River Severn takes the top spot, flowing across both England and Wales.
3. The Thames is over 18 miles at its widest… – As with any body of water, the width of the Thames varies dramatically. The widest part of the Thames is 18 miles (29km) across, which is at its mouth.
4. …And just 18 meters at its narrowest! The narrowest point can be found in a village called Lechlade where it is just 59 feet (18m) across. 
5. The depth of the river also varies – The depth of the River Thames varies drastically but the very deepest part is around 60 feet (20m), which in comparison to other rivers around the world is not actually that deep. 
6. 214 bridges cross the River Thames – From cute wooden slatted footbridges to iconic structures like London Bridge, each one assists people’s journeys from one side to the other! 
7. The Thames has the second-largest flood barrier in the world – Operational since 1982, the Thames Barrier is a retractable defense system developed to protect the city of London from the dangers of exceptionally high tidal surges. Incidentally, the largest flood barrier on earth is located in the Netherlands. 
8. The Thames boasts the longest river walk in Europe – If you love walking then this one’s for you! Starting in Gloucestershire and meandering its way for 296 km all the way to the Thames Barrier, this is indeed the longest river walk in the whole of Europe! (You could also walk in London instead!)
9. The Thames is teeming with life – It may be surprising that despite its rather murky outlook the river is home to over 110 species of fish, as well as other wildlife such as otters, voles, and eels.
10. There are more than 180 islands in the Thames – Some are accessible only by footbridge, some by road, and others – like the well-known Pharaoh’s Island – are only accessible by boat. Thirty are inhabited by single houses or houseboats, and these are all highly sought-after locations. 
11. There are 45 locks on the non-tidal section of the Thames – These are large chambers, which are built across the river, with gates at either end that are there to hold back the water. Boats enter the lock, the gates shut and the lock then fills or empties of water until the boat has reached the next level on the river. This is definitely something cool to watch while you are exploring the Thames path. 

Historical River Thames Facts

As you know, understanding history is an important part of visiting London – so here are some curious historical facts about the river that defined this city in the first place.

12. The Thames has a long history – Humans have been settling on the banks of the Thames and the surrounding areas since at least the Neolithic period which is around 10,200 BC!
13. The Thames was once dubbed “The Great Stink” – For centuries the River Thames was used as a dumping ground for the capital’s waste. As the city’s population grew, so did the amount of sewage. The hot summer of 1858 elevated the stench to an unbearable level and it became so bad that Parliament had to be suspended! This earned the river this rather lousy nickname. What followed was the development of London’s sewer system, which was built in 1865. 
14. The Thames was once home to a polar bear! – When it comes to River Thames facts, this one is a bit quirky! In 1251 the King of Norway sent King Henry III an elaborate gift: a real, live polar bear?! This lived, with the King’s other zoo animals, which included lions and an African elephant, at The Tower of London. The bear was tethered on the banks of the Thames and was able to swim and fish there. 
15. Julius Caesar once mentioned the Thames in his writing – The very famous Roman Emperor, Julius Caesar wrote about the river Thames after his second expedition to Britain and visit to Londinium in 54 BC.
16. The Thames used to host Frost Fairs on its surface – Until 1814, the river used to freeze in the winter. Londoners would take advantage of this by holding Frost Fairs on its icy surface. There would be stalls selling food and drinks and lots of fun activities like football, dancing, and horse racing. There was, as you may imagine, also plenty of ice skating.
17. The Thames saw one of England’s worst river disasters – This is one of the sadder River Thames facts on the list. In this disaster, over 640 people tragically lost their lives when two passenger boats collided on the River Thames in 1878. 

Other Fun Facts about the River Thames 

There are lots of other curious facts about the Thames that you might find interesting too…

18. The Thames provides 2/3 of London’s drinking water – It may be hard to imagine, given the murky brown color of the Thames. However, having been treated and filtered, around 2/3 of the capital’s drinking water comes from the river. So if you have ever stayed in London, then you have probably drunk some Thames water – or at least washed your hair with it!
19. The Thames plays host to a very famous annual boat race – Known across the world, “the Boat Race” between Oxford and Cambridge Universities takes place annually on the River Thames in . The race was first held way back in 1829 and since then, only three massive events have prevented it from going ahead; World War I, World War II, and the pandemic. 
20. Over 200 rowing clubs use the river – You might spot them out on nice summer mornings!
21. The name of the Thames has a fascinating meaning – It is believed that the River Thames takes its name from the Latin “Tamesis” which means “dark.” The water in the Thames is dark and murky so this may be quite apt!
22. The Oxford stretch of the Thames is commonly known as the River Isis – Strangely, it was wrongly thought its original name “Tamesis” was a combination of Thame and Isis. It actually wasn’t but the name stuck anyway!
23. The River Thames Police is the world’s oldest police force – The River Thames Police force has been patrolling the waters since 1798, making it the oldest continually serving police force in the world. Over the years the tasks of the force have varied and evolved. When it was first established the increase in trade and the chaotic conditions on the river meant there was ample opportunity for river pirates to make off with stolen cargo which gave the force plenty to do. Today the force works more on river safety.
24. The Thames has inspired many artists over the centuries – Many famous artists have been inspired by the River Thames. The American artist, James McNeill Whistler was captivated by the river and included it in a number of his paintings. Other artists who were enchanted by the dark depths of the river include Claude Monet, Camille Pissarro, and James Tissot.
25. There are many shipwrecks littering the bed of the River Thames – It’s a little eerie to think that the Thames is the final resting place for many ships and boats. These vessels sadly met their fates while sailing down the river, either sunk by storm, error of the crew, or indeed by enemy attack.
26. Occasionally some very special visitors swim their way up the river – It may not happen often but very rarely dolphins have been known to swim up the river as far as London city!
27. The Thames may flood London in the future – Rising sea levels, predominantly due to climate change, may mean that the Thames Barrier may only protect the city from flooding for so long. Scientists believe that in around 2060 Londoners may need to find alternative methods of flood defense. We hope you have enjoyed reading our facts about the River Thames!

Have any other questions about the River Thames, or have you heard another interesting fact I should add to the list? Let me know in the comments below!