Ishigaki (Yaeyama)

Ishigaki is the southwesternmost dive base in Japan, anchoring the Yaeyama group within the Iriomote-Ishigaki National Park and the Okinawa Prefecture. Its signature draw is the reef manta ray (Mobula alfredi), which the IUCN SSC Shark Specialist Group recognises as aggregating regularly and predictably over cleaning stations in Kabira Bay — at the two adjacent sites 'Manta Scramble' (found by Kabira-area guides in the 1980s) and 'Manta City Point', roughly 300 m apart — and in the Yonara Channel between Iriomote and Kohama islands. The Kuroshio Current funnels nutrient-rich plankton past the islands, and mantas gather to feed and be cleaned in groups of up to roughly 14 animals, with the season running May–October and peaking September to early October. Beyond the mantas, Ishigaki fringes the Sekisei Lagoon, the country's largest coral reef, which historically held over 360 coral species but has suffered repeated mass bleaching (1998, 2007, a 2016 event in which the Environment Ministry recorded ~70% of surveyed coral dead, and 2022 when over 90% bleached) compounded by red-soil runoff and crown-of-thorns starfish — so reef condition varies markedly by site and year. Diving is day-boat from Ishigaki port or the Kabira area; most reef sites are shallow (10–25 m) with little current, while channel and offshore sites such as Yonara Channel can run very strong and are drift dives for experienced divers. The operational risk window is the typhoon season, roughly June to October with a peak from August into early October.

• The IUCN SSC Shark Specialist Group designates the Yaeyama Islands an Important Shark and Ray Area for reef manta rays (Mobula alfredi), which aggregate regularly and predictably over cleaning stations in Kabira Bay (the 'Manta City' and 'Manta Scramble' sites, ~300 m apart) in groups of up to roughly 14 animals between May and October, with a peak from September to early October.
• Ishigaki fringes the Sekisei Lagoon, the largest coral reef in Japan, set within the Iriomote-Ishigaki National Park and historically home to over 360 coral species — though the reef has been hit by repeated mass bleaching and is the focus of an ongoing multi-stakeholder restoration effort formed in 2006.
• Bleaching history is real and well documented: after widespread events in 1998 and 2007, Japan's Environment Ministry reported in January 2017 that over 70% of surveyed coral in the Sekisei Lagoon had died following the 2016 marine heatwave, and in 2022 the Ministry announced more than 90% of the lagoon's coral had bleached — so divers should expect reef condition to vary markedly by site and year.