During the cold war USSR developed a submarine called “Typhoon”, it was the biggest and most technologically developed submarine on world. It was called in “Shark” in NATO documents and western media. To develop this submarine and get ahead of western submarines it drained the USSR of money but to this day they still stand as one of the most developed submarines in world and also the biggest, with more over than 170 meters (515 feet) long and 23 meter (70 feet) wide. via (ru_submarine)
These bestial submarine can carry 20 ballistic nuclear missiles and there were only six of those built.
Only 3 left intact, but are staying now out of service with armament control blocks detached according to the agreement between USSR and USA signed.