| Udone-shima | |
| Native Name: | 鵜渡根島 |
| Location: | Izu Islands |
| Archipelago: | Izu Islands |
| Area Km2: | 0.4 |
| Length M: | 1500 |
| Width M: | 550 |
| Elevation M: | 210 |
| Country: | Japan |
| Country Admin Divisions Title: | Prefecture |
| Country Admin Divisions: | Tokyo |
| Country Admin Divisions Title 1: | Subprefecture |
| Country Admin Divisions 1: | Ōshima Subprefecture |
| Country Admin Divisions Title 2: | Village |
| Country Admin Divisions 2: | Niijima |
| Population: | 0 |
is a volcanic, deserted island located in the Philippine Sea approximately 150km (90miles) south of Tokyo in between Toshima and Nii-jima, in the northern portion of the Izu archipelago, Japan.
The island is the remnant of an andesite lava dome with sheer sides, the only visible portion of a submarine volcanic caldera. The above sea-level portion has a surface area of approximately 0.4 square kilometers, with a summit height of 210m (690feet). The main island is surrounded by a number of rocks.
Despite its small size, the island was formerly inhabited during the Meiji period by a small community of fishermen who also engaged in sericulture, or silk farming. A small Shinto shrine still exists on the island.
See also: Nii-jima. This island shares many similarities in its biodiversity with neighboring islands such as Nii-jima. Being surrounded by rough sea, vicinity to the island is rather difficult to visit in fact, and this made the natural environments of the islands and nearby atolls protected. Indo-Pacific bottlenose dolphins that newly inhabited around Udone-shima as their residential range has been expanded wider even onto Honshu coasts. Larger sharks inhabit the area. Historically, a breeding colony of now-extinct Japanese sea lions once existed on the island as well.