The external shots of the island were used (as they approached it in the boat)
but the interior shots were filmed in a studio. Because of the crumbling nature of the structures, it's a considered a dangerous place to even walk around.
James Bond, meet UNESCO. The UN agency has just recognized as a world historic site an island off Japan better known as the lair of a James Bond villain, Raoul Silva, Hashima island looks too creepy to be real — and its true history is even creepier.