Okinawa is a car island — the aquarium, the castles and the war memorials are strung along a hundred kilometres of main island, and the good water is on ferries out of Naha.
Okinawa Churaumi Aquarium
The main draw on the main island: the Kuroshio Sea tank holds whale sharks and manta rays, and the coral tank beside it is lit by natural sunlight rather than lamps. It sits inside Ocean Expo Park at Motobu, about two hours from Naha by car or express bus — arrive in the afternoon once the coach groups have gone.
Shurijo Castle Park
The royal seat of the Ryukyu kingdom, on the hill above Naha and reached by the Yui Rail monorail to Shuri. The Seiden main hall burned down in October 2019 and is being rebuilt; the walls, gates, grounds and museum are open, and the reconstruction work itself can be watched from a viewing area.
Himeyuri Peace Museum
In Itoman at the southern end of the island: the account of the schoolgirl nursing corps conscripted during the 1945 Battle of Okinawa, told largely in survivors' own words. Open 9:00–17:25 daily with last admission at 17:00, year round. Allow ninety heavy minutes.
Cape Manzamo
A 20-metre limestone cliff on the Onna coast with a grass headland above it and the much-photographed elephant-trunk arch below. Entry is 100 yen for everyone over primary-school age; the facility runs 8:00–20:00 from March to October and 8:00–19:00 from November to February, and closes in typhoons.
Kerama Islands day trip
The Keramas lie west of Naha and have the clearest water in the prefecture. Both the fast Queen Zamami and the slower Ferry Zamami 3 run from Tomari Port in Naha; schedules, fares and live sailing status are on Zamami village's own site, and summer sailings need booking ahead.