A Swedish ship of the line lost in 1788, her timbers and guns preserved by brackish water that shipworm cannot live in, laid…A Swedish ship of the line lost in 1788, her timbers and guns preserved by brackish water that shipworm cannot live in, laid out as a marked underwater trail with information boards you read at 16 metres. The Baltic is the largest underwater museum in the world, no shipworm, cold water and low salinity mean wooden hulls survive for centuries. Finland's answer was to open the wrecks rather than close them, building marked parks, Porkkala's guides divers round four wrecks, so protection and access work together. Anchorage: The Helsinki archipelago is a maze of sheltered anchorages, and the Gulf of Finland is a summer cruising ground with almost no tide. Hazards: Cold water and silt that goes to zero visibility if disturbed. The wreck is an archaeological site with underwater signboards and rope guides. Plus