Surrounded by the Pacific Ocean, the Ogasawara Islands are located approximately 1,000 kilometers (620 miles) south of Tokyo, Japan. The more than 30 islands and marine areas of the archipelago spread over 400 square kilometers (154 square miles). The string of small subtropical and tropical islands is home to a variety of endemic plants and animals, some of which are rare and endangered.
This island chain is considered the only place on Earth where geological features visible from the ground show how an island arc is formed when oceanic plates collide. The archipelago was formed between 65 million and 1.8 million years ago by undersea volcanoes. Most of the islands drop sharply into the ocean with sea cliffs ranging from 50 to 100 meters (164 to 328 feet) in height. The rugged topography has little flat land. Pillow lava can be found in some places, while in others the limestone surface has been etched, fluted and pitted to create stunning rock formations. Sharp color contrasts are formed between the white sand and the clear, deep blue sea.
The remote oceanic islands were formed in isolation and have never been connected to a continent. Because of this they are often referred to as the Galapagos of the East. Native animals and plants colonized the islands by dispersal over ocean waters and have undergone a unique evolutionary process. New species that evolved on these islands are still being discovered. The concentrated rates of endemism are exceptional. The archipelago is home to 195 endangered species of birds, and a critically endangered species of bat known as the Bonin flying fox. More than 40% of the plants and 75% of the trees are endemic, as are 100 of the 106 species of land snails.
Vegetation ranges from moist and dry forests in the lowlands to palmdominated forests on dry, rocky mountain slopes. Scrub forests can be found on mountain ridges and on the exposed tops of sea cliffs.
Marine areas within the Ogasawara Archipelago are home to significant populations of whales, dolphins and sea turtles. The underwater landscapes contain abundant collections of coral and tropical fish.
The islands are also known as the Bonin Islands, and many battles were fought in the area during the Second World War, most notably at Iwo Jima. Today, the two inhabited islands of Chichijima and Hahajima have a combined population of about 2,500 and can only be reached by a more than 25hour ferry trip from Tokyo.
The islands are an outstanding example of the ongoing evolutionary processes in ocean island ecosystems, but invasive species of plants and animals introduced to the islands as early as 1830 have become serious threats. There is a need to minimize their impact and restore the original ecosystems.