105 atmospheric ( i.e. , not underground ) nuclear tests were conducted there , many of which were of extremely high yield . 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 which were inhabited , and some that had not been evacuated
Castle Bravo
Castle Bravo
Toxic hotspot