The treasures of the Thames
One of the newest trends in leisure used to be a full-time job for the desperately poor. In eighteenth-century London, so-called “mudlarks” would walk along the banks of the Thames, looking for lost goods they could scavenge and sell. Today, tourists take the same walk and look for the same kinds of things, but for a different reason: they want to hold a piece of history in their hands—and unlike the originals, modern participants in mudlarking are actually paying for the privilege.
Mudlarking is a bit like magnet fishing (Glimpse, June 2020) but for history: it's a task that rewards patient, attentive people, especially the ones who can come up with an interesting backstory to explain a rusted or rotting artifact they've found. And like magnet fishing, it's highly amenable to YouTube content, since the discoveries can be surprising.
So far, mudlarking is under-monetized. There are paid tours in London and large cities, but sellers of metal detectors haven't yet added “mudlarking”-related keywords to their product descriptions, despite growing search volume around the world. It's a market that could exist in many other places too: many of the locations that have had big cities for the longest time are located on rivers, which made transportation easier.