This photo of my photoalbum was taken in Okinawa.

Okinawa Prefecture (沖縄県, Okinawa-ken?, Okinawan: Uchinā) is Japan's southernmost prefecture, and consists of hundreds of the Ryukyu Islands in a chain over 1,000 km long, which extends southwest from Kyūshū (the southwesternmost of Japan's main four islands) to Taiwan. Okinawa's capital, Naha, is located in the southern part of the largest and most populous island, Okinawa Island, which is approximately half-way between Kyūshū and Taiwan. The disputed Senkaku Islands (Chinese: Diaoyu Islands) are also administered as part of Okinawa Prefecture.

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water yet shallow enough to be a hazard to ships. Many reefs result from abiotic processes—deposition of sand, wave erosion planning down rock outcrops, and other natural processes—but the best-known reefs are the coral reefs of tropical waters developed through biotic processes dominated by corals and calcareous algae. Reefs can be created artificially either by special construction or through deliberately sinking ships, but one can argue that these "reefs" are not real ones, as it is seldom the case that an artificial obstruction would be created that is a hazard to shipping. These structures are usually created to enhance physical complexity on generally featureless sand bottoms in order to attract a diverse assemblage of organisms, especially fish. Thus, "artificial reef" is a misnomer, though firmly established as the term used for man-made underwater habitat structures.