Ishinamigawa

Ishinamigawa is a river-mouth surfing spot in Hyuga known for powerful, hollow waves with both right and left directions. The break is described as working best when East or Northeast swells line up, and when West or Southwest winds provide offshore grooming for the wave faces. Wave size is commonly described as starting to work under 1 meter and holding up to around 2.5 meters (and beyond), with normal ride lengths typically reported in the 50 to 150 meter range. Sources also emphasize that the best conditions depend on tide movement, with mid-tide movement often cited as producing better wave shape. Safety-wise, the approach and lineup can be challenging: rocks and reef are reported hazards near the river mouth, and pollution/debris risk can be elevated, particularly after heavy rainfall and river runoff. Additionally, paddling out can be very difficult when the swell builds past roughly 2 meters, so conditions should be judged carefully before committing. Timing is generally strongest in the September to October window (typhoon/late summer into early autumn), though weekend crowding is noted even during good periods—weekdays are typically quieter.