Izu Peninsula

The Izu Peninsula juts out from Honshu, Japan’s main island, into the Pacific Ocean just west of Tokyo. Its coastline is deeply carved, and the interior is mountainous. Once called Izu Province, it now belongs to Shizuoka Prefecture. Covering about 1,421 square kilometers, it was home to an estimated 473,942 people in 2005, with most residents living along the northern and eastern shores.

Geology

Geologically, the peninsula formed where the Philippine Sea Plate collides with the Okhotsk Plate at the Nankai Trough. The Philippine Sea, Amurian, and Okhotsk plates meet at a triple junction near Mount Fuji, and the peninsula itself sits on the Philippine Sea Plate. The south is largely made of breccia, while the central and northern areas are dotted with heavily eroded volcanoes.

The Amagi Mountain Range runs through the middle, featuring Mount Amagi (1,406 meters), Mount Atami (773 meters) in the east, and Mount Daruma (982 meters) in the west; its eastern and western arms extend underwater into Sagami Bay and Suruga Bay. The main river, the Kano, flows north through a graben valley shaped by tectonic forces. Because of this geology, the region experiences frequent earthquake swarms and tsunamis, and hot springs are abundant.

Administration

Administratively, the entire peninsula falls within Shizuoka Prefecture, split into eight cities—Atami, Itō, Izu, Izunokuni, Numazu, Mishima, and Shimoda—and five towns in Kamo District: Higashiizu, Kawazu, Matsuzaki, Minamiizu, and Nishiizu.

Economics

Tourism drives much of the economy, drawing visitors from the Kantō region to onsen resorts in Atami, Shuzenji, and Itō. Sea bathing, surfing, golf, and motorcycle touring are also popular. The peninsula borders Mount Fuji and is part of Fuji-Hakone-Izu National Park.

In 1937, the southwest coast—covering Matsuzaki, Nishiizu, and Minamiizu—was named a National Place of Scenic Beauty. Besides tourism, agriculture and fishing are key, with Izu ranking as one of Japan’s top wasabi producers; local dishes often feature wasabi. Still, these industries aren’t enough to stop a heavy outflow of people, especially the young, to Greater Tokyo and Shizuoka.

Railway

Getting there is easiest by rail: the Tōkaidō Shinkansen stops at Atami in the northeast and Mishima in the northwest. The JR Itō Line and Izu Kyūkō Line run along the east coast to Shimoda, though service is less frequent due to sparse population. Central Izu is served by the Sunzu Line as far as Shuzenji. The west coast has no train service.

By road, expressways connect the peninsula; from Tokyo’s Yōga Interchange on the Tōmei Expressway, it’s 103.3 kilometers to Numazu. A branch at Atsugi leads to the Odawara-Atsugi Road, continuing past Odawara to Yugawara, Atami, and Shimoda. National Routes 135, 136, and 414 also serve the area. Two scenic drives—the Izu Skyline and Western Izu Skyline—offer views of nature and Mount Fuji, popular with car and motorcycle enthusiasts.

The Odakyu Electric Railway runs local buses from Odawara and Hakone, and an internal bus network exists but is infrequent. For air travel, the peninsula’s airspace was the site of Flight JAL 123’s accident on August 12, 1985, when an aft pressure bulkhead explosion killed 520 people, one of the deadliest air disasters ever.