Yoron island in Kagoshima Prefecture is the best resort place in clean sea water, much better than Okinawa, Ishigaki, Miyakojima.
It takes only 35-minute flight from Naha Airport, 2-hour in taking ferry from Motobu, Okinawa.
The best place in the island is Yurigahama, which is the land at a low tide during a limited period between spring and autumn. It takes 3000yen in round trip each person to go to the island by boat.