harmaja is a small island with a lighthouse south of suomenlinna between katajaluoto and kuivasaari. the island has been used as a pilot station and the current lighthouse was built in 1883. at the start of the war two guns were placed on the island. these were relocated in october 1914 when construction of a 6-inch canet battery began. the small island did not have the necessary building materials, and sand, gravel and cement had to be brought in with barges. the guns were installed in february 1915 and the battery was finished in september 1916. harmaja battery is the smallest of the long range batteries and the guns are not located in straight line but in an l-shaped formation. a breakwater surrounds the southern end of the island.