K-429: Only Russian Submarine in History to Sink Twice.During the Cold War, the Soviet Union faced numerous submarine accidents, exacerbated by its struggle to maintain a formidable military. One notable incident involved the K-429, a Charlie-class nuclear-powered cruise missile submarine.In 1983, amid heightened U.S.-Soviet tensions, K-429 was hastily deployed with an inexperienced crew. A dive led to a disastrous flooding, killing 16 men.The submarine sank but was later raised and returned to service. However, it sank again in 1985 at dockside. These incidents underscored the Soviet Union’s difficulty maintaining military assets, highlighting the risks of Cold War pressures.