The wreck of a warship Kronprins Gustav Adolf

Located off Helsinki, the Kronprins Gustav Adolf wreck park was opened in 2000. It is the first underwater park of its kind in the Baltic Sea. The park presents a wreck which was once the pride of the Swedish Navy, i.e. the Kronprins Gustav Adolf, which was sunk in 1788.

A war memorial

In the early 1780s, King Gustav III of Sweden was planning a war against Russia. His aim was to take back for Sweden those eastern parts of Finland and the Baltic States which had been previously lost to Russia. In preparation for the war, the Swedish naval fleet was modernised and the ship of the line Kronprins Gustav Adolf, completed in 1784, was just one of the new warships constructed.

This new battleship was large, measuring approximately 50 metres in length, with a complement of 550 crew members and soldiers. Although originally planned to have no more than 62 cannons, more than 70 such guns have been found in the wreck. The ship belonged to the Swedish offshore fleet, which was sent to the eastern Gulf of Finland as early as June 1788, even though war had not yet been declared.

Cannon balls and a cannon on top a partial cannonball crate.

The pride of the Swedish offshore fleet sinks

In the summer of 1788, the war between Sweden and Russia began and fierce battles were fought at sea. In August, the Russians made a surprise attack when the Swedish offshore fleet was moored near Viapori, i.e. present-day Suomenlinna Island, off Helsinki.

While other Swedish ships managed to flee, the Kronprins Gustav Adolf was delayed because the crew had trouble weighing anchor. Eventually, the large ship began to get under way, but as it made its escape, it ran aground on a previously unknown reef lying at a depth of about four metres.

The ship was damaged, rupturing its hull and causing the gunpowder stores begin filling with water. Upon facing a superior enemy force, the ship’s crew surrendered to the Russians. Thereafter the ship exploded, went adrift, and finally sank to its current position.

Later, the fateful shallows where the battleship ran aground became known as the Gustav Adolf reef, a name that can still be seen on sea charts to this day.

A diver inspects the cannonball crate.

The wreck was found in 1985 – five years later the wreck park was opened

The wreck of the Kronprins Gustav Adolf was found in 1995, following a side-scan sonar survey of the seafloor off Helsinki by the Naval Research Institute. The side-scan revealed a large wreck at a depth of approximately 20 metres. Divers from the Finnish Coast Guard inspected the site and found it to be the wreckage of a large wooden warship. Between 1997 and 1999, the Finnish Heritage Agency investigated the wreck together with volunteer divers, after which the wreck park was opened in 2000.

There is a guided path around the wreckage area, with information signs about the ship's history and its construction. The wreckage consists of the bottom part of the vessel, including anchors, cannons, and cannonballs, as well as other ship's equipment and diverse objects.

There is free access to the wreck park. The park opens every year in June and closes in the autumn.

Read more about the wreck park and related instructions for visitors from the Finnish Heritage Agency's website!

How and why is this site protected?

This wreck is a fixed ancient remnant protected by the Antiquities Act (295/1963). The law protects all wrecks and parts thereof that can be presumed to have sunk at least 100 years ago. While diving to wrecks protected by the Antiquities Act is permitted, it is prohibited to tamper with or dive inside a wreck.

Check out the wreckage information in the Antiquities Register!

The park is marked with a buoy to which boat can be attached.


The wreckpark can be visited with a private boat or an organized tour. The park is located off Helsinki, several nautical miles southwest of the Harmaja Lighthouse. The wreck park has free access and is marked with a buoy which can be used to moor a boat.

At the bow and stern of the wreck are ropes and buoys for divers to descend and ascend. A guided rope path circles the wreckage area. The wreck can be explored closely as long as it is not interfered with or otherwise damaged. The park is the responsibility of the Finnish Heritage Agency.

Finnish Heritage Agency's Mapservice

N: 6658841 E: 384658 (ETRS-TM35FIN)