The Mark 90 Betty was a nuclear depth charge developed by the United States in 1952. With a length of 10 ft 2 in, a diameter of 2 ft 7.5 in, and a weight of 1,243 lb, it utilized a Mark 7 nuclear warhead, with a yield of 5-10 kilotons. Its purpose was to serve as an anti-submarine weapon for the United States Navy. All units had been retired and withdrawn from service by 1960. A test of the Mark 90 was conducted in 1955 as Operation Wigwam. The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter. ... Depth Charge used by U.S. Navy later in World War II The depth charge is the oldest anti-submarine weapon. ... Background Mark 7 nuclear bomb at USAF Museum Mark 7 Thor was the first tactical nuclear bomb adopted by US armed forces. ... A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ... Alvin in 1978, a year after first exploring hydrothermal vents. ... The United States Navy, also known as the USN or the U.S. Navy, is a branch of the United States armed forces responsible for conducting naval operations. ... Wigwam underwater burst Operation Wigwam involved a single test of the Mk-90 Betty nuclear depth bomb. ...

On September 25, 1959, a "Betty" was lost in Puget Sound after the aircraft it was in was forced to "ditch". The casing was never recovered, though it did not have its nuclear core installed at the time. September 25 is the 268th day of the year (269th in leap years) in the Gregorian calendar. ... Puget Sound Puget Sound (pronounced IPA ) is a sound connected to the Pacific Ocean via the Strait of Juan de Fuca in the Pacific Northwest of the United States. ...

References

• James N. Gibson, Nuclear Weapons of the United States: An Illustrated History (Schiffer Publishing, 1996): Chapter 12, "Nuclear Anti-Submarine Weapons".