Rongelap Atoll is a coral atoll located in the Pacific Ocean. It consists of 61 islands and forms a legislative district within the Ralik Chain of the Marshall Islands. The atoll covers a total land area of 8 square miles (21 km2) and encloses a lagoon spanning approximately 1,000 square miles (2,600 km2).
The atoll is historically significant due to its proximity to United States hydrogen bomb testing in 1954. It was severely devastated by fallout from the Castle Bravo test, which led to long-term radiation exposure and health issues for the local population. Although residents were initially moved back to the atoll in 1957 as part of Project 4.1, they were eventually forced to relocate due to ongoing health concerns.
Following unsuccessful attempts to have the U.S. government facilitate a move, the inhabitants sought assistance from the environmental group Greenpeace. The vessel Rainbow Warrior transported the residents, their belongings, and over 100 tons of building materials to the island of Mejato in the Kwajalein Atoll, located 180 kilometers away.