You've entered an enormous building scoured by ocean tides and haunted by hulking machines, slowly rusting away. It looks like the set for a post-apocalyptic movie, but it's actually a real-life Soviet submarine base, left over from the Cold War.

Kraternyy, a secret base (1987-1994) on an uninhabited volcanic island named Simushir, Kuril Islands

(via Austronesian Expeditions)

Object 825, a hydraulic engineering structure for nuclear defense and a shelter for fourteen submarines in Balaklava, Ukraine

(via English Russia and samnamos)

Bunker Alsou or Object 221 (also known as PCP BSF, Protected Command Point Black Sea Fleet) in the Crimea

(via Alexfotos)

A nuclear shelter for Pacific Fleet submarines, Pavlovsk, Russia

(via Kata-Katafota)

A base in Hara, Estonia, built between 1956 and 1958, used until 1991

(via Dmitri Korobtsov, Andrea Luht and Syn)

Liepaja, an ice-free harbor in the Baltic Sea, once a submarine base for 16 submarines and a nuclear deposit. There was also a closed town named Karosta.

(via Andrius Vanagas, Hugo Kintzler, Mika Meskanen, Pexi from Helsinki Rock City, Rats'n'Ruins and Cold War Sites)