In 1965 and 1967 astronauts training to for the Moon landing came to Iceland. One of the reasons was the landscape; the black sand and the lava. The formation of the landscape is different from most parts of the world since Iceland has tons of ash, lava, and black sands. It is a distinctive feature of the landscape. And the people training the astronauts probably felt that they could familiarize them with the landscape on the Moon by letting them walk in their moon boots and full gear here in Iceland.