Five days later, the United States Atomic Energy Commission established the Pacific Proving Grounds.

[2] The United States conducted 105 atmospheric and underwater (i.e., not underground) nuclear tests in the Pacific, many with extremely high yields.

While the Marshall Islands testing composed 14% of all U.S. tests, it composed nearly 80% of the total yields of those detonated by the U.S., with an estimated total yield of around 210 megatons, with the largest being the 15 Mt Castle Bravo shot of 1954 which spread considerable nuclear fallout on many of the islands, including several that were inhabited and some that had not been evacuated.

[4] Scientists have calculated that the residents of the Marshall Islands during their lifetimes will be diagnosed with an added 1.6% (with 90% uncertainty range 0.4% to 3.4%) cancers attributable to fallout-related radiation exposures.

Because of the large amount of atmospheric testing, and especially the Castle Bravo accident of 1954, many of the islands which were part of the Pacific Proving Grounds are still contaminated by nuclear fallout.

Scientists calculated in 2010 that during the lifetimes of members of the Marshall Islands population, potentially exposed to ionizing radiation from weapons test fallout deposited during the testing period (1948–1958) and from residual radioactive sources during the subsequent 12 years (1959–1970), perhaps 1.6% (with 90% uncertainty range 0.4% to 3.4%) of all cancers might be attributable to fallout-related radiation exposures.

During that time, payments averaging about $18 million per year were made to the peoples of Bikini, Enewetak, Rongelap, and Utrik for medical and radiological monitoring, and in response to claims.

[11] The first use of the Pacific Proving Grounds was during Operation Crossroads, the first nuclear testing done after the atomic bombing of Hiroshima and Nagasaki.

Both tests used a flotilla of obsolete vessels from World War II with the intent of learning the effects of nuclear weapons on naval fleets.

The most notable was Castle Bravo, which was the first deployable (dry fuel) hydrogen bomb developed by the United States.

The fishermen aboard the Japanese fishing vessel, the Daigo Fukuryu Maru, were additionally exposed and one man died soon after from complications of radiation sickness, resulting in considerable international controversy.

Thirty-six weapons were detonated at sites in the Pacific Ocean in the vicinity of Christmas Island and Johnston Atoll as part of Operation Dominic I.

[13] The portion of the Dominic series of tests that were high altitude nuclear explosions were known as Operation Fishbowl, though not all were successful (one detonated on launchpad and resulted in a substantial plutonium contamination).

Here are the islands listed in clockwise fashion starting with left side of the major inlet into the lagoon in each atoll.