Yes, Bikini Atoll is still radioactive. More than 70 years after the United States detonated 23 nuclear weapons there between 1946 and 1958, background gamma radiation on Bikini Island averages around 190 millirem per year. That is nearly double the 100 millirem per year exposure limit agreed upon by the U.S. and Marshall Islands governments, and permanent resettlement remains unsafe without major cleanup efforts.
How Radioactive Is It Today?
The contamination is not uniform across the atoll, but Bikini Island itself, the largest landmass, carries the heaviest burden. Soil samples show cesium-137 levels between 455 and 636 becquerels per kilogram, which is dramatically higher than nearby Rongelap Island (13 to 15 Bq/kg) and orders of magnitude above what you’d find in uncontaminated soil anywhere else in the world.
Plutonium concentrations in the northern Marshall Islands are 10 to 1,000 times higher than the levels detected near Fukushima after the 2011 nuclear disaster. Americium-241, a decay product of plutonium that builds up over time, has been measured at 80 to 175 Bq/kg on Bikini Island. These are long-lived isotopes. Plutonium-239 has a half-life of 24,000 years, meaning the soil contamination will persist for millennia without active removal.
For context, the Marshall Islands Nuclear Claims Tribunal set 15 millirem per year as the safe annual dose for cleaned-up land. Bikini Island’s 190 millirem average is more than 12 times that threshold.
Why It’s Still Uninhabitable
External radiation from the ground is only part of the problem. The real barrier to resettlement is the food chain. Cesium-137 in the soil gets absorbed by coconut palms, breadfruit trees, and other crops that would form the basis of any subsistence diet on the atoll. Eating locally grown food would multiply a resident’s internal radiation dose well beyond what background measurements alone suggest.
The lagoon floor compounds this. Bomb craters at the bottom of the lagoon act as reservoirs, slowly releasing dissolved radioactive material, including cesium-137, strontium-90, and iodine-129, into the water column. Fish, aquatic plants, and other marine organisms absorb these isotopes, meaning locally caught seafood carries contamination too. Plutonium, which binds tightly to sediment particles, is particularly persistent in this environment.
A 2016 study published in the Proceedings of the National Academy of Sciences confirmed that gamma radiation on Bikini Island remains well above 100 millirem per year over natural background. The U.S. Government Accountability Office has stated plainly that permanent resettlement without remedial measures is not recommended.
Remediation Efforts So Far
Scientists have tested one promising technique: adding large amounts of potassium to the soil. Potassium and cesium are chemically similar, so when soil is flooded with potassium, plant roots preferentially absorb the potassium and take up far less cesium-137. In field experiments, applying potassium at high concentrations reduced cesium levels in coconut meat to just 3 to 5 percent of their original levels. Even moderate applications cut contamination by two-thirds.
The catch is scale. Treating the entire island’s soil at effective levels (1,000 to 2,000 kilograms of potassium per hectare) would require sustained, large-scale agricultural intervention. And potassium treatment does nothing about plutonium or americium in the soil, nor does it address the contaminated lagoon sediments. A full cleanup would need to tackle multiple isotopes across both land and water, a project no government has committed to funding.
Can You Visit Bikini Atoll?
Despite the contamination, Bikini Atoll does receive a small number of visitors, almost exclusively technical divers coming to explore the sunken warships in the lagoon. The U.S. sank a fleet of target vessels during the nuclear tests, and the wrecks now sit at depths of 50 meters or more. Residual radiation exposure for divers in the water is negligible, provided they don’t remove any artifacts from the wrecks, which is both hazardous and forbidden.
Diving at Bikini is heavily restricted. You need advanced technical diving certifications, at least 100 logged dives, and previous deep wreck experience. Operators limit divers to two technical dives per day with mandatory four-hour surface intervals. Brief visits to the island’s surface for a beach barbecue are sometimes offered, but no one lives there. Short visits to the island’s surface expose you to far less radiation than long-term habitation would.
What This Means for the Bikinians
The original inhabitants of Bikini Atoll were relocated in 1946 before the testing began. A brief resettlement attempt in the 1970s was abandoned after residents showed elevated levels of cesium-137 in their bodies from eating local food. Today, the Bikinian community lives primarily on Kili Island and Majuro, hundreds of miles away.
The gap between current contamination levels and the safety thresholds set by the Marshall Islands government remains enormous. At 190 millirem per year average background radiation, with contaminated food and water on top of that, Bikini Atoll is not close to being safe for permanent habitation. The isotopes driving most of the current exposure, cesium-137 (half-life of about 30 years) and americium-241 (half-life of 432 years), will continue declining, but the timeline for natural decay alone to bring levels within safe limits stretches well into the next century for cesium and far longer for americium and plutonium.