[2] In March 1978, Götaverken Arendal shipyard in Gothenburg, Sweden was awarded a contract for the construction of the world's largest floating dry dock for the Soviet Union.

During the final test, which involved finding out how fast the submerged dock could be deballasted, two ballast water tanks partially collapsed due to underpressure.

The floating dry dock was hastily towed back to Arendal with visible denting on the shell plating and the shipyard workers scrambled to fix the damage.

[3][5] The grounding of the brightly-illuminated PD-50 was witnessed by Soviet border guards who later described the incident as if a small city had appeared from the sea, only to be driven on the rocks by the storm.

This caused outrage in naval circles, as the shipyard was one of the few in Russia with facilities capable of docking the country's largest surface vessels.

[7][8] On 30 October 2018, the Russian aircraft carrier Admiral Kuznetsov was damaged when PD-50 suddenly sank under it,[9] causing one of the dock's 70-ton cranes to crash onto the ship's flight deck.

[11] In July 2019, Zvezdochka Ship Repair Center JSC [ru] and Saint Petersburg company Investments Engineering Construction (I.I.S.)