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.”