Setonaikai National Park (瀬戸内海国立公園, Setonaikai Kokuritsu Kōen) is a national park comprising areas of Japan's Inland Sea and of ten bordering prefectures. Designated a national park in 1934, it has since been expanded several times. It contains about 3,000 islands, known as the Setouchi Islands, including the well-known Itsukushima. As the park is formed of many non-contiguous areas and covers a tiny proportion of the Inland Sea's total extent, control and protection is problematic, with much of the wider area heavily industrialized.