What to know
Izu Oshima (伊豆大島) is the largest of the Izu Islands, a volcanic archipelago administered by Tokyo, lying close to the Izu Peninsula. Situated about 100 kilometers south of the capital, the island can be circled by car in roughly an hour. It's a popular escape for Tokyoites seeking a quick getaway.
At the island's core stands Mount Mihara, an active volcano rising 758 meters. It gives rise to numerous attractions and hot springs. The northern and western coasts offer beaches for snorkeling, sunbathing, and other summer activities. Oshima is also famed for its camellia flowers, which bloom nearly everywhere from January to March.
Mount Mihara is a frequently erupting volcano, with its most recent eruption in 1990. A major eruption in 1986 produced spectacular explosions and lava flows that cascaded from the summit caldera down the northwestern slopes, forcing the evacuation of over ten thousand residents. Today, visitors can hike to the summit to view the caldera up close and learn about volcanology at the Museum of Volcanoes.