Among the rocky shores and wooden summerhouses of Dalarö, an exclusive Swedish summer retreat, there was little to indicate anything other than a typical summertime scene on the Stockholm archipelago.
It was only as the coastguard boat reached a discreet yellow buoy that there was any suggestion of the 17th-century shipwreck lying, preserved, 30 metres beneath it. “STOP,” read a sign. “Marine cultural reserve.”
Bodekull, built by the English shipbuilder Thomas Day, is believed to have run aground in 1678 and sunk while transporting flour to the Swedish naval fleet in Kalmar, down the coast in south-east Sweden.
Thanks to the Baltic’s brackish water protecting the wreck from shipworms, the 20-metre-long ship remains on the seabed, upright and largely intact, full of relics that are still being discovered. Two of its three masts poke up towards the sky in their original position.
But now Bodekull faces a human threat to its existence. Authorities say that it is among thousands of historic wrecks across the Nordics that are at risk from plundering.
On a monitoring operation last week, experts shared photographs with the Guardian that show that objects are vanishing from shipwrecks.
Those responsible are believed to be a diverse array of offenders, from light-fingered sport divers in search of souvenirs to criminal gangs looking for high-value objects to sell. Such is the scale of the problem that the coastguard is now regularly sending divers down to monitor at-risk sites.
“The plundering problem isn’t just a Swedish problem, it’s a Baltic Sea problem,” said Jim Hansson, a marine archaeologist at Vrak, the museum of wrecks, citing the sea’s low salinity and comparatively shallow average depth of 55 metres.
These unique conditions, as well as the existence of an estimated 100,000 shipwrecks, make the Baltic a “mecca for marine archaeologists,” he said. But it’s also increasingly attracting looters.
Around Stockholm alone, Hansson knows of six wrecks that have been looted by international and Swedish divers.
Hansson and his colleagues started to get a sense of the scale of the problem when they were setting up the museum seven years ago and realised, during a series of dives, how many objects were missing. They have since teamed up with the coastguard and police to better protect the wrecks.
“Sweden has one of Europe’s longest coasts so it’s a lot of water to guard and it isn’t easy,” said Hansson.
Authorities are keen to show that shipwreck looting is taken seriously.
In September, four Swedish men aged between 57 and 70 were given suspended sentences – and three of them community service – for multiple cases of gross antiquities violation after they were caught with 100 objects looted from shipwrecks. Among the objects found in their possession were a 17th-century iron cannon and clay mugs.
Patrick Dahlberg, a coastguard commander, said the divers were caught with their haul after they were found on a wreck they did not have permission to be on.
Coastguard divers normally work on environmental disasters, inspect ships for drugs and weapons and help police looking for murder weapons. “It is very unique for us to be part of this,” he said.
In recent years, several objects on Bodekull have been moved around and a decorative ceramic bowl has gone missing.
On Tuesday, coastguard diver Patrik Ågren said he didn’t see any evidence of tampering as he emerged from recording the contents of a tool drawer on the ship containing planes, sledgehammers, a basket and carpentry equipment.
“There’s a lot of sediment and sludge, small particles,” he said. “When somebody has been there, swum or moved something, then it is usually clear.” Video footage he recorded during the dive will be compared with previous footage to check for changes.
But on a later dive they discovered that a wheel on a cannon had been removed, a deck beam collapsed and a wine bottle moved since they last visited in January. While some of the changes may have been caused by nature, Hansson said it was difficult to see how the wheel and wine bottle could have been moved without human intervention.
On a big coastguard ship anchored nearby, usually used for environmental rescue and which contains a sauna for the crew, marine archaeologists from Vrak showed footage from the latest dive, as well as evidence they previously recorded of missing objects.
Hansson said removing relics from wrecks prevented them from building a full picture of the type of ship, where it was going and what it was doing.
“We collect all the puzzle pieces just like a police or coastguard investigation,” he said. “That’s why it is super important that objects are not moved because it is like ripping the pages from a book. In the end all you will have left is an empty shell.”
Amid heightened tensions with Russia after its invasion of Ukraine, allegations of spying and Sweden’s hopes of imminently joining Nato, it is a critical time for the Baltic.
But Hansson said that cultural monuments could also be used in war. “What happened with Nord Stream [gas pipeline bombings] could similarly happen with national cultural heritage monuments like shipwrecks. The first thing that happens with big conflicts is that you erase a nation’s integrity and history.”
