Okinawa mainland Kouri-jima [Kouri island] : The beautiful island you can go to by bus from Naha! Snorkeling Paradise.
You may be disappointed by the urban atmosphere of Naha city, which is the capital of Okinawa prefecture. The beaches there are strictly controlled and snorkeling is forbidden. I visited Kouri-jima by express bus and a free shuttle. And it was a really satisfying snorkeling spot.