Nazumado

Nazumado is one of Hachijō Island's most popular dive sites, located on the island's west side facing the smaller island of Hachijō Kojima. The strait between the two islands channels powerful currents and swells, and because of this exposure the site can be dived safely fewer than 100 days per year. Entry and exit are made by walking backwards down a slippery old boat ramp while holding a rope, and conditions during a dive can change dramatically in both strength and direction of current.

The terrain is entirely volcanic rock, beginning in a relatively shallow and sheltered bay before reaching a large rocky ledge called Umanone, which has an arch at around 15 metres. Passing through the arch leads to the more exposed section: a series of ridges extending toward the open sea, with the maximum depth of 25 metres reached at the end of the outermost ridge. Current conditions determine whether divers can complete the full circuit to that point and return safely to the ramp.

Marine life at Nazumado rewards the effort. Large schools of reef fish gather on current-swept days, and the exposed position brings in amberjacks, tunas, and trevallies. Scalloped hammerhead sharks and thresher sharks are sometimes seen on early morning dives, particularly between May and July. Green turtles are common, especially in the shallows, and Japanese Pygmy Seahorse live on certain rocks at around 10 metres depth. Spotted eagle rays, moray eels, octopuses, nudibranchs, and shrimps are also present, and dolphins are occasionally encountered.