From 1946 to 1958, the United States detonated 23 nuclear devices at seven test sites inside Bikini Atoll. They had a combined yield of about 77 Mt.
How radioactive is the atoll today?
"It is safe to walk on all of the islands...The Advisory Group reaffirmed: although the residual radioactivity on islands in Bikini Atoll is still higher than on other atolls in the Marshall islands, it is not hazardous to health at the levels measured. Indeed, there are many places in the world where people have been living for generations with higher levels of radioactivity from natural sources - such as the geological surroundings and the sun - than there is now on Bikini Atoll...By all internationally agreed scientific and medical criteria...the air, the land surface, the lagoon water and the drinking water are all safe. There is no radiological risk in visiting the lagoon or the islands. The nuclear weapon tests have left practically no cesium in marine life. The cesium deposited in the lagoon was dispersed in the ocean long ago.
"The main radiation risk would be from the food: eating locally grown produce, such as fruit, could add significant radioactivity to the body...Eating coconuts or breadfruit from Bikini Island occasionally would be no cause for concern. But eating many over a long period of time without having taken remedial measures might result in radiation doses higher than internationally agreed safety levels."
https://www.bikiniatoll.com/whatrad.html
How radioactive is the atoll today?
"It is safe to walk on all of the islands...The Advisory Group reaffirmed: although the residual radioactivity on islands in Bikini Atoll is still higher than on other atolls in the Marshall islands, it is not hazardous to health at the levels measured. Indeed, there are many places in the world where people have been living for generations with higher levels of radioactivity from natural sources - such as the geological surroundings and the sun - than there is now on Bikini Atoll...By all internationally agreed scientific and medical criteria...the air, the land surface, the lagoon water and the drinking water are all safe. There is no radiological risk in visiting the lagoon or the islands. The nuclear weapon tests have left practically no cesium in marine life. The cesium deposited in the lagoon was dispersed in the ocean long ago.
"The main radiation risk would be from the food: eating locally grown produce, such as fruit, could add significant radioactivity to the body...Eating coconuts or breadfruit from Bikini Island occasionally would be no cause for concern. But eating many over a long period of time without having taken remedial measures might result in radiation doses higher than internationally agreed safety levels."
https://www.bikiniatoll.com/whatrad.html