Sandarmokh (Сандармох; Karelian: Sandarmoh) is a forest massif 12 km (7.5 mi) from Medvezhyegorsk in the Republic of Karelia where victims of Stalin's Great Terror were executed. Their number is unknown, but is estimated to be in the thousands. More than 58 nationalities were shot and buried there by the NKVD in 236 communal pits over a 14-month period in 1937 and 1938.

At least 1,000 victims were from the Solovki special prison on an island in the White Sea. It was long thought that the barges carrying them were deliberately sunk on the way to the mainland, drowning all the prisoners on board. Others were rounded up during the Great Terror in Karelia, in accordance with quotas for prisoners, 'enemies of the regime', and a variety of "national operations". According to available documentation at least 6,000 were shot and buried at Sandarmokh.

Today Sandarmokh is a memorial to the crimes of Stalin and his regime and since 1998 has been the focus of an international Day of Remembrance on 5 August every year.

On 27 October 1937, 1,116 prisoners were loaded onto three barges and taken from Solovki to the mainland for their sentences at Sandarmokh.

Only in 1996, thanks to the efforts of Veniamin Ioffe [ru] (1938–2002), co-chairman of the Memorial research centre in St Petersburg, documents were found in the archives of the Arkhangelsk department of the Federal Security Service (FSB) throwing light on the subsequent fate of the "first Solovki transport". These included the lists of those men and women who were to be shot. One died before he could be executed; four more were sent to other parts of the Gulag.

After years of work on the ground in Karelia by Yuri Dmitriev, this documentary evidence pointed the way to the identification on 1 July 1997 of the Solovki prisoners' last resting place and that of another 5,000 executed individuals. By the suggestion of Ioffe, the location would subsequently be given the local (Karelian) name "Sandarmokh" (sometimes spelled "Sandormokh"), by the name of an abandoned khutor (small settlement) shown in old maps of the area. The story of that search and discovery was told in 2017 by Irina Flige, head of the Memorial Education and Information Centre in St Petersburg. In 2015 Dmitriev recounted how he, Flige and the late Veniamin Ioffe had found the burial site. According to documents found in the FSB archives in Arkhangelsk, there were people of 58 nationalities among those shot at Sandarmokh.

Three hundred personal plaques and memorials have been erected around the site since 1997 to commemorate the many victims of this killing field, both individually and as representatives of particular nations and cultures, and an international Day of Remembrance has been held there every 5 August since 1998. In 2010, Patriarch Kirill of the Russian Orthodox Church led the mass for the slain victims of Stalin at Sandarmokh, just as he and his predecessor Alexy II have done, every year since 2007, at the Butovo killing field near Moscow.

Today, thanks to the Memorial Society, to Veniamin Ioffe and Yury Dmitriev, over 5,000 of the dead of Sandarmokh can again be named and remembered individually, at the place where they lie buried.