I went to Shikine Island in May 2007 at the same time as Niijima Island. They are about an 11 hour ferry ride away from Tokyo on the overnight ferry, which leaves at 2200 from Tokyo's Takeshiba pier. Please see the Niijima page for photos of the ferry, it will be posted soon. Note that I made a mistake while naming some of the photos, Matsugashima Onsen is really Matsugashita (under the Pine tree) Onsen.