Cold War tunnel under Crimea

Under Mount Tavros in Balaklava, Crimea, lies a 602-meter-long tunnel known as Object 825 GTS, built between 1953 and 1961 during the Cold War. The structure was designed to accommodate up to seven submarines simultaneously and was built to withstand a 100 kiloton bomb, approximately seven times the power of the Hiroshima bomb.

Facility's military features

The facility included a dry dock, mechanical workshops, fuel tanks, and a torpedo arsenal. It was used by the 14th submarine division of the Black Sea Fleet, serving as a hidden, secure location for submarines during the Cold War.

Abandonment and conversion

The base was abandoned in 1993 following the collapse of the Soviet Union and later looted for its metal. It was converted into a Cold War museum in 2003 and remained open to the public.

Post-annexation status

After Russia's annexation of Crimea in 2014, the site was integrated into Russian military museum structures, though its tourist function continued. In 2021, the Russian navy moved an old Soviet Romeo-class submarine, the S-49, into the tunnel as a museum exhibit.

Recent military claims

In February 2025, the Crimean Tatar resistance group Atesh claimed, based on satellite images and Telegram videos, that Russia was reactivating the site for military purposes. The group alleged that floating barriers had been installed at the entrance to the bay, ostensibly to counter Ukrainian naval drones.

Unconfirmed allegations

These claims have not been independently confirmed.