This Swedish ship of the line was sunk off Helsinki during the Russo-Swedish war in 1788.
In the beginning of August 1788, Swedish ships were on patrol in the Gulf of Finland. Some of the ships, including the Kronprins Gustav Adolf, were anchored for the night outside the fortress of Viapori (Sveaborg / Suomenlinna) off Helsinki. In the following morning, on the 6th of August, Russian vessels surprised the anchored Swedish ships. All of these except for the Gustav Adolf managed to escape. The Kronprins Gustav Adolf had difficulties when lifting one of its anchors, but in the end she managed to leave for the fortress. When fleeing, the ship struck a shoal that was previously unknown and lost the topmast of the mainmast. Also the bottom of the ship was damaged and water flew into the gunpowder store. After a few shots the ship had to surrender to the Russians. People later gave the shoal the name of “The Gustav Adolf ‘s Shoal”. The name can be found on naval charts of today.
The wreck was discovered by the Finnish Navy in 1995. It lies a few nautical miles southwest from the lighthouse island of Harmaja. The remains of the ship lie at 18-20 meters and are in part scattered on an area of approximately 100 x 100 meters. The wreck consists of the bottom of the hull, the sides, which have fallen down, different parts of the structure, cannons, cannon balls, and a variety of loose articles. All in all 71 cannons have been found at the site. Three of these were raised, conserved and examined. There are also two big iron anchors at the wreck.