Honshu is the largest, most populated island of Japan and is regarded as the Japanese mainland. Most of Japan’s early history took place in its southern region. Also, with the metropolitan areas of Tokyo, Yokohama, Osaka, and Kobe, it is Japan’s economic center. Honshu is also home to Japan’s highest mountain, Mount Fuji, and its largest lake, Lake Biwa.
Honshu has an area of 87,992 square miles (227,898 square km) and contains almost three-fourths of the total number of prefectures of Japan. The coastline extends 6,266 miles (10,084 km). Along this extensive coastline divers will find temperate ocean conditions influenced by the Kuroshio Current that flows from the South China and Yellow Seas. Under these waters grow amazing kelp forests that are home to a mix of warm and cold-water marine life.
Diving in Honshu offers a variety of sites be it ocean, river, or lake. Popular dives include the Ito Shark Scramble where hundreds of banded hound sharks, stingrays, and groupers swarm helmeted divers, swimming with dolphins in Mikurajima, and encountering whales in Ogasawara. A large number of macro species, especially nudibranchs, are also found in Honshu, making this region home to some of the best diving in Japan.
Honshu is home to many large cold-water marine species such as the Nomura’s jellyfish, one of the largest jellyfish species in the world, the giant Pacific octopus, and the gentle, wild dolphins of Noto Peninsula, one of only four locations where you can swim with dolphins in Japan. Other amazing Japanese marine life encounters in Honshu include the large Asian sheepshead wrasse, the yellow-spotted bandfish, and hordes of hammerhead sharks found congregating in the summer just off Mikomoto Island. Want to go shark diving in Japan? Visit Tobishima May to early July when hundreds of docile banded hound sharks gather to spawn inside the cave.