In 1968 there was an incident when a Soviet November-class submarine tracked an American carrier group traveling at 31 knots (57 km/h). This led the United States Navy to develop the Los Angeles-class submarines, whose reported speed is 30–32 knots (56–59 km/h).
There are established reports and manufacturer's claims that would indicate two (or perhaps more) submarines are capable of speeds exceeding 30 knots (56 km/h). In 1965, USS Albacore reported a speed of 33 knots (61 km/h), but this was not an official record. The Akula (Russian: shark)-class vessel is reportedly capable of travelling submerged at 35 knots (65 km/h), its predecessor, the Alfa class, could attain short speed bursts of 40–45 knots (74–83 km/h) while submerged. There are claims that the Russian titanium submarine K-162 reached 44.7 knots (83 km/h) on sea trials, fully submerged, in 1969. However, due to the rather secretive nature of these vessels, confirmations of these numbers are not present.
The British Spearfish torpedo designed to counter high-speed Russian submarines, such as the Alfa-class submarine, is reputed to have a speed in excess of 70 knots (130 km/h). The Russian rocket-powered supercavitating torpedo VA-111 Shkval is reportedly capable of speed in excess of 200 knots (370 km/h). German press reports of an underwater anti-torpedo missile named Barracuda that allegedly reaches 220 knots (400 km/h). The United States Navy has contracted with the General Dynamics Electric Boat Division to support development of the Underwater Express, an undersea transport capable of controllable speeds up to 100 knots (185 km/h) through supercavitation.