Japan

Japan is rarely the first country that comes to mind for scuba diving, and that is precisely why it rewards the diver who makes the effort.

The focal point for most visiting divers is Okinawa, a chain of subtropical islands stretching south toward Taiwan, surrounded by some of the healthiest coral reefs in the country. Water temperatures range from 22–29°C depending on season, visibility regularly reaches 25–30 meters, and the reef life — Napoleon wrasse, sea turtles, reef sharks — is dense and relatively undisturbed.

But the landmark that puts Japan on every serious diver's list is the Yonaguni Monument, 30 km off the coast of Japan's westernmost island. At 25 meters depth lies a massive stone structure of contested origin — flat terraces, right-angle steps, carved channels, and vertical walls that look nothing like natural erosion. Whether it is a human-made ruin from a long-lost civilization or a spectacular geological formation, nobody has conclusively settled. What is settled: it is extraordinary to dive. Hammerhead sharks congregate at Yonaguni in winter, patrolling the blue water above and around the formation.

Mikomoto Rock, off the Izu Peninsula near Tokyo, is one of the best hammerhead sites in East Asia — scalloped hammerheads school at 30–40 meters in summer and autumn. Kerama Islands, west of Okinawa's main island, offer pristine coral gardens and reliable humpback whale encounters from January through March.

Best season: Okinawa dives year-round but peaks April–October. Yonaguni for hammerheads is December–March. Plan around a 7mm wetsuit for cooler months.

Japanese dive operations are exceptionally well-organized, English-speaking guides are available at all major sites, and the infrastructure — from rental equipment to liveaboard boats — is first-rate.