The island is a stratovolcano with a basaltic composite cone, dating from the late Pleistocene period, between 10,000 and 15,000 years ago.

The highest elevation, Mount Mihara (三原山, Mihara-san), is an active volcano with a height of 758 meters (2,487 ft).

The island has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports populations of Japanese wood pigeons, Ijima's leaf-warblers, Izu thrushes and Pleske's grasshopper warblers.

Izu Ōshima is a popular site for tourists[6] from both Tokyo and Shizuoka due to its close proximity to the mainland.

Mihara and Izu Ōshima were also featured in Koji Suzuki's Ring and its film adaptation as pivotal locations for the story.

The island has a peripheral role in The Dancing Girl of Izu by Yasunari Kawabata subsequently adapted for film multiple times.