In the 19th century, after Russia gained sovereignty over Finland, the island was fortified by Russian occupiers. In 1906 unrest preceding the Russian Revolution broke out here and on neighbouring Suomenlinna, then known as Viapori, in the form of a mutinous armed uprising. The mutineers’ luck turned when an ammunition cellar blew up on the second day of the rebellion. The explosion shattered the rocks along the shore leaving a deep cleft in the cliffs. The force of the blast was so strong that windows were broken in the Helsinki district of Kallio several kilometres away.
To reach the island of Kuninkaansaari walk along the breakwater that forms a causeway between the southeast corner of Vallisaari and Kuninkaansaari.