Which Oceanian country was the site of the Castle Bravo nuclear test?

The Oceanian country that was the site of the Castle Bravo nuclear test is the Marshall Islands. The test took place at Bikini Atoll, part of the Marshall Islands, on 1 March 1954.

Castle Bravo was the first test in the United States’ Operation Castle series of high-yield thermonuclear weapons. The device produced a yield of about 15 megatons of TNT—around two and a half times the predicted six megatons—because scientists had underestimated the contribution of lithium-7 in the weapon’s fuel. It remains the most powerful nuclear device ever detonated by the United States.

The unexpectedly large explosion created a vast radioactive-fallout plume. Marshallese communities on nearby atolls, US personnel and the crew of the Japanese fishing vessel Daigo Fukuryū Maru were exposed. The contamination forced further evacuations and contributed to long-term health, environmental and political consequences for the Marshallese people.

Christmas Island was also used for later British nuclear tests, but not Castle Bravo. French Polynesia hosted French tests, while Kiribati was not the country containing Bikini Atoll. Bikini remains a UNESCO World Heritage site associated with the nuclear-testing era.