Soviet submarine B-427, Soviet submarine museum in Long Beach, United States.

The Soviet submarine B-427 is a Project 641 Foxtrot-class diesel-electric attack submarine moored beside the Queen Mary in Long Beach. Its dark grey hull has a rounded bow, a tall conning tower with a curved front face and a small oval emblem, and a black periscope mast. A red-star flag flies near the tower's rear, and a metal railing runs along the deck.

The submarine left the shipyard in 1971 and served for over two decades in the Soviet Pacific Fleet. After the Cold War ended, the navy decommissioned the craft in 1994.

The vessel carries the designation B-427 and belonged to the Foxtrot class, known for its diesel-electric propulsion. Visitors recognize the typical lines of Soviet submarines from that era when viewing the craft from the pier.

The submarine sits directly beside the Queen Mary and has been closed since 2015 due to extensive repair work. Visitors can view the exterior from the dock, but boarding is not currently possible.

During its three years at the Australian National Maritime Museum, the boat drew over 700,000 visitors, among them intelligence analysts from several nations who came in the first weeks it was on display. Because it was still Russian Navy property on lease, an Australian ex-submariner was commissioned into the Russian Navy to command it.