Go to the beach. The best beaches are in the sparsely populated northern part of Okinawa and on the tiny islands surrounding Okinawa.
The area around Naha is dominated by port facilities and seawalls. An exception is Naminoue Beach by the Naminoue shrine.
If you are staying in Naha, a good alternative is to take the ferry to the Keramas, the collective name for Tokashiki, Zamami, Aka, and several smaller islands. The water in the Keramas is pristine and is known for world class diving and the tourism on the islands is geared for visiting divers. A shallow "discovery" dive for unlicensed divers costs about 10,000 yen.
The ferry leaves from Tomari port in Naha and cost 2,800 yen to 3,540 yen round trip. There is more expensive faster ferry also available.
The closest island is Tokashiki. The ferry leaves Tomari Port at 10AM and arrives at 11:10AM. The afternoon ferry leaves Tokashiki at 3:30PM or 4PM depending on season. On Tokashiki, take the shuttle to Aharen beach for great snorkeling and swimming. http://www.vill.tokashiki.okinawa.jp/en
The ferry to Aka and Zamami take a little longer. The ferry goes first to Aka then Zamami. The beaches on Zamami are within walking distance although it’s a bit of a hike. Ask the visitor center at the Zamami ferry terminal about getting around. http://www.vill.zamami.okinawa.jp/
North of Naha, Tropical Beach is by the Ginowan Marina and the Okinawa Convention Center.
Araha Beach is in the Hamby area.
Sunset Beach is by the Mihama American Village.
The most popular beaches in the northern part of the island are on the Onna coast along Hiway 58 between Yomitan and Nago.
(More info to be added. If you have recommendations, Contact us and let us know.–editor)