Report by Immi Wallin, DSAT Technical Diving Division
A great example of co-operation between divers and the Marine Archaeology Unit which belongs to Finnish National Board of Antiquities happened this summer. A treasure chest was found, documented, studied and lifted in coastal waters of Helsinki.
A scuba diver found copper plates a couple of years ago near an island in front of Helsinki. He brought one to the Marine Archaeology Unit where they identified it as “plootu” which is so called plate-money manufactured in Sweden from 1644 until 1776. At that time the value of the money was just the value of the metal it was made of and since other countries in Europe made “Dalers” from silver and gold, the Swedish copper Dalers had to be really big. A ten Daler plootu weighted almost 20 kilos. This type of money was of course very unpractical and even though Sweden had lots of copper, the plate-money was in use for only about 130 years.
The position of the place where the find was made was not precise and no more plate-money was found in the area even there were a couple of attempts made. I heard about the case and made a search in June with side scan sonar and ROV. After one day mapping the sea bed by side scan sonar and flying with a ROV a pile of plate-money was found – a bit outside the area where the initial plootu Daler was found. The ROV video recording was brought to the Marine Archaeology Unit in Helsinki and next week we went back together with researchers, conservation specialists and numismatist packed on board my vessel. It came out that the find was a wooden treasure chest from the 1670’s and included several plootu Dalers and coin Dalers. There were also some material which could have been the sack for the coins. Everything was lifted by diving and placed immediately to specific containers which we had brought along.
At the moment the plootus and coins are in conservation and hopefully some day in an exhibition together with the remains of the chest. How the lonely chest ended up to this location is unknown. It could have been a ship capsized in a storm, or a sledge falling through the ice.