Bikini and Bikini

Mushroom-shaped cloud and water column from the underwater Baker nuclear explosion of July 25, 1946. Photo taken from a tower on Bikini Island, 5.6 km away.

25 July 1946, 65 years ago: Nuclear weapon test Baker at Bikini Atoll, part of Operation Crossroads. The purpose of Operation Crossroads was to investigate the effect of nuclear weapons on naval ships. Crossroads consisted of two detonations, each with a yield of 23 kilotons: Able was detonated at an altitude of 158 m on July 1, 1946; Baker was detonated 27 m underwater on July 25, 1946.

Bikini Atoll, with Bikini Island boxed in the northeast. The crater formed by the Castle Bravo nuclear test can be seen on the northwest cape of the atoll.

The Crossroads tests were the fourth and fifth nuclear explosions conducted by the United States (following the Trinity test and the bombings of Hiroshima and Nagasaki). They were the first of many nuclear tests held in the Marshall Islands and the first to be publicly announced beforehand and observed by an invited audience, including a large press corps.
The test resulted in the radioactive contamination of all the target ships by the underwater Baker shot. It was the first case of immediate, concentrated local radioactive fallout from a nuclear explosion (the fallout from an air burst is global, held in the stratosphere for days and widely dispersed). Chemist Glenn Seaborg, the longest-serving chairman of the Atomic Energy Commission, called Baker "the world's first nuclear disaster".
Because of radioactive contamination, Bikini remained uninhabited as of 2010, though it is occasionally visited by sport divers.

November 1946: Fashion model Dovima wearing bikini, Montego Bay, Jamaica.

The bikini is typically a women's two-piece swimsuit. The modern bikini was invented by French engineer Louis Réard in 1946, who named it after Bikini Atoll in the Pacific, the site of the Operation Crossroads nuclear weapon tests in July that year. The bikini is perhaps the most popular female beachwear around the globe, according to French fashion historian Olivier Saillard due to "the power of women, and not the power of fashion". Predecessors of the bikini date to antiquity and the Greco-Roman world. Art dating from the Diocletian period (286-305 AD) in Villa Romana del Casale, Sicily, depicts women in garments resembling bikinis in mosaics on the floor.

The "Bikini girls" mosaic showing women exercising, first quarter of the 4th century AD. 

Villa Romana del Casale, Sicily.