London may not have a beach, but the River Thames runs right through the city, and since it's a tidal river, the river banks are uncovered every day.
In the 18th and 19th centuries, many poor people in London searched the riverbanks for trinkets that had been dropped into the water and cargo that had fallen off passing boats, and they would sell the treasures they found. Being a mudlark—someone who searched for these items—was a recognized occupation until the early 20th century.
But mudlarking these days is more like beachcombing or treasure hunting for those interested in London's history.
Mudlarking Along the Thames
The Thames is now one of the cleanest metropolitan rivers in the world, but it used to be regarded as London's trash can. Thames mud is anaerobic (without oxygen) and preserves whatever it consumes, which makes the 95-mile foreshore (the part of the shore closest to the water) of the tidal Thames one of the richest archaeological sites in Britain.
Mudlarking is the urban equivalent of beachcombing (looking on the beach for "treasures" washed up by the sea). There are serious mudlarking enthusiasts who are registered and have all the necessary equipment, and then there are amateur archaeologists and the rest of us who are intrigued by London's past being displayed on the foreshore every day.
As of September 2016, a license is required to search for anything on the foreshore, even if you are just looking without an intent to touch or remove anything.
You can apply to the Port of London Authority for a license, and the staff there can give clear guidance on what you will be allowed to do and where.
It is very important that any object found on the foreshore that could be of archaeological interest is reported to the Museum of London so that potentially everybody can benefit from the find.
Through this scheme, the mudlarks have helped build an unparalleled record of everyday life on a medieval river.
If you intend to take home what you find, you will need to get an export license.
This is an urban setting, so you are most likely to find everyday objects that people have thrown away like pottery, buttons, and tools. It is extremely unlikely you will find a bag of diamonds or a sack of gold.
The most common item to find is a clay pipe, which is usually broken and often sitting right on the surface. These were smoking pipes and were sold pre-filled with tobacco and although they could be re-used, they were generally thrown away, especially by the dock workers, which explains why there are so many in the river. While that sounds like the equivalent of a modern cigarette butt and not exciting, they date back to the 16th century.
Remember to take plastic bags with you for your finds and do wash everything in clean water before letting others handle it.
The most important information you need for mudlarking safely is found on the daily tide tables. The Thames rises and falls by more than seven meters (about 23 feet) twice daily as the tide comes in and out, and the water is cold.
Check the exit points because the river rises very quickly and has an exceptionally strong current. The steps to the river can be slippery so climb with care.
Wash your hands or wear disposable gloves because the area is muddy. There is also a risk of contracting Weil's disease (spread by rat's urine in the water), and sewage in storm conditions is still discharged into the river. Infection is usually through cuts in the skin or through the eyes, mouth or nose. Medical advice should be sought immediately if ill effects are experienced after visiting the foreshore, particularly flu-like symptoms such as temperature and body aches. All in all, be careful not to touch your eyes or face before your hands are clean. An anti-bacterial wash can help before you give those hands a good scrub.
Wear sturdy footwear because it can be muddy and slippery in places.
Be sensible and don't go mudlarking on your own.
Finally, note that if you venture onto the foreshore, you do so entirely at your own risk, and you must take personal responsibility for anyone you mudlark with. In addition to the tides and currents mentioned above, hazards include raw sewage, broken glass, hypodermic needles, and wash from vessels.
Where to Mudlark
You can try treasure hunting in some prime locations in central London. You can mudlark under the Millennium Bridge outside the Tate Modern on the South Bank or move over to the North Bank near St. Paul's Cathedral. Outside Gabriel's Wharf can be a fun place to check the shore, and the areas around Southwark and Blackfriars bridges on the North Bank are also worth checking out. You could also have a look around Canary Wharf if you're visiting the Museum of London Docklands.