Southwest of Okinawa, the snorkeling at Miyako Island offers snorkeling on the large coral reef called Yabiji. The Yabiji reef is located north of Miyako Island and is 17km long from north to south. It is a popular site to see clownfish. During the spring tides, the reef is typically slightly above the surface water.
The snorkeling off Okinawa is best from May through October when the water temperature is more enjoyable for snorkelers. However, that is also the prime time for the stinging Habo Jellyfish, which is a type of box jellyfish. Since 2012, the local authorities have been posting more snorkeling restrictions/prohibitions at Okinawa beaches, so make sure to look for signs and follow them to avoid being arrested.
To reach the snorkeling in Okinawa by air, you will need to fly into Okinawa Naha Airport (OKA) on southern end of island.
Overall, Miyako Island is the 10th most popular snorkel dive spot of all 12 snorkeling dives in Japan.