Signs of geothermal activity can be found along the southern coast where hot springs occur.

The legend that Niijima and Shikinejima were formerly one island, and were separated by a giant tsunami triggered by the 1703 Genroku earthquake has no basis in geology.

The island, along with Nii-jima and some uninhabited islets nearby, have been recognised as an Important Bird Area (IBA) by BirdLife International because they support populations of Japanese murrelets, Japanese wood pigeons, Pleske's grasshopper warblers, Ijima's leaf-warblers and Izu thrushes.

[2] The history of human settlement on Shikine-jima dates to prehistoric times, and archaeologists have found number remains from the Jōmon period on the island.

Access to Shikine-jima is by ferry from Takeshiba Sanbashi Pier in Tokyo, operated by Tokai Kisen.