Swedish treasure hunters have captured images of a mysterious object in the Baltic Sea . The object, which is about 10 feet long and 5 inches wide, was spotted by two men on board an inflatable boat off the coast of Sweden last week. The imaging technique involves pulling a sonar `` towfish '' -- that essentially looks sideways underwater - behind a boat , where it creates sound echoes to map the sea floor below . Deep-sea salvage company Ocean Explorer uses sonar imaging to search for wrecks .
Swedish treasure hunters have captured images of a mysterious object in the Baltic Sea . The object, which is about 10 feet long and 5 inches wide, was spotted by two men on board an inflatable boat off the coast of Sweden last week. Deep-sea salvage company Ocean Explorer uses sonar imaging to search for wrecks .