Rent a car (with GPS/SatNav/Kanabi)and go see the Aquarium north of the island. It is quite the drive, but well worth it.

It features the worlds highest/widest view of an aquarium and it has a very diverse selection of animals.

On the way back you should picknick on Soporo island which you can get to by crossing a white bridge. At the far end of the main road you will end up on a marvelous beach

Added tip: Go when it is very sunny. You might want to spend your time on the beach in those conditions, but unlike most aquariums, this one uses natural light in the tanks.
So the sunnier it is, the more vibrant the colors. On a beautiful day this is probably the most beautiful aquarium you will ever see.

Go diving!
That is, if you are certified and are positive about what you are doing below the surface.

The Kerama islands have utterly magnificent dive spots and if you are lucky you will see whales on the way over there. Also the view is fantastic while doing your surface interval.

That said, if you haven't dived before, it might be better to not do it if you cannot find a decent English speaking instructor. The language barrier might prove to be difficult.

PS: if you stay in Naha, head for Rehab Bar (on the main shopping road, 2nd level, 300m north'ish from MacDonalds) and ask the -Canadian- owner and patrons if they know any us military divers doing some teaching on the side.

Prepare for great storms and diving. Here is the third best place on earth for scuba. Also, terrible for tropical storms and typhoons.

If you in Gushikawa you HAVE to eat at Casa de Taco and Capital Steakhouse...THE 2 BEST PLACES TO EAT ON THE PLANET!

make sure to check out yakniku viking (the local cab drivers know it as "try") its a restaurant were you cook your own food on a grill built into your table. very friendly staff, and great food.

This is an Air Force military base in Okinawa,Japan. Not very exciting unless your a Marine like I was stationed there.

Airforce base.Military stuff. about it.

Okinawa Island, was the sight of a major WW II battle of epic proportions. The U.S.military presence here is hard to ignore. Okinawa has crystal blue waters like many other islands in the Pacific, but due to it's more Northern latitude is not a major vacation spot. The people are subdued and hard working. They are related to, but not wholly Japanese, though Japanese is spoken and understood here.

Okay this kind of place is not for the new traveler! If you are not familiar with the term "Culture shock," come and visit Japan. At the airport, there are English translation but once your are out in the Japanese cities, you're on your own. Make sure you learn a few phrase like "Do you speak English?" That help me on the phone. It is a wonderful, exotic, and life changing experience. Especially being American or European, be prepared to be gawked at as the tallest, fattest, well basically bigger than any Japanese people, particularly Okinawa. Oh yeah, on the island everyone wears hats, long sleeves, gloves, carries umbrellas, long pants, etc. to guard from the sun. It took me a while to get used to people walking around completely covered up. I did love the fish market, but get there early to see and even buy fresh catch of tropical colors. The Japanese people, it seems, really do appreciate all opportunities that the ocean provides as meals. Itoman is wonderful to see the suicide caves, tunnels, and cliffs from World War II. I was enthralled. Hedo point is the most northern spot in Okinawa. It worth a drive becasue you pass Okuma beach where you can camp out right on the ocean front, includes resaurant, BBQ pits, and other emenities.

The Beach Tower Hotel and Chulala Spa!