The waters around one of the world’s most remote inhabited islands, in the middle of the South Atlantic Ocean, are set to become the fourth largest completely protected marine area in the world, and the largest in the Atlantic.

Tristan da Cunha, a British territory, is 2,300 miles east of South America and 1,600 miles west of South Africa. To reach it requires a seven-day boat trip from South Africa, and once you’re there, “you feel so much like you’re at the edge of the world,” says Jonathan Hall, the head of the U.K. overseas territory unit at the Royal Society for the Protection of Birds (RSPB).

Now, this four-island archipelago will be the site of a marine sanctuary that spans 265,347