The Solovki prison camp (later Solovki prison), located on the Solovetsky Islands in the White Sea, was a large forced labor camp for political prisoners of Imperial Russia, and later the Soviet Union. During the Soviet era, as "Solovki Special Purpose Camp" it became a model where the NKVD developed and tested security measures, "living conditions", work production norms for prisoners, and different methods of repression. The exact number of prisoners who went through the camp during 1923–1939 is still unknown, but estimates range between tens and hundreds of thousands. It was the "mother of the GULAG" according to Aleksandr Solzhenitsyn. He estimated that in 1923 there were "no more than 3,000" prisoners, but that by 1930 the number had jumped to "about 50,000" with another 30,000 imprisoned at the nearby railroad transit point of Kem.
Historically, the Solovetsky Islands were the location of the famous Russian Orthodox Solovetsky Monastery complex, which repelled foreign attacks during the Time of Troubles, the Crimean War, and the Russian Civil War.
By Lenin's decree, the monastery buildings were turned into Solovetsky Lager' Osobogo Naznachenia (SLON), that is, the "Solovki Special Purpose Camp". The acronym of the camp name is a sullen word play for those who speak Russian: slon means "elephant". It was one of the first "corrective labor camps", a prototype of the Gulag system. In the beginning of 1924 sometimes the double name was used Severnye (Solovetskiye) Lagerya OGPU (Northern (Solvki) camps of OGPU).