To fully explore Okinawa, you really need a hire car. There are buses that run up and down the island and there is a short mono-rail in Naha City, but to get anywhere adventurous or off the beaten track you will need a car. As Okinawa gets prettier and more photogenic the further away you get from the urban sprawl of the capital, I’d say this is money well spent. In Japan you drive on the left, so if you have driven in the UK driving is fairly easy.
I opted for a minivan from a company called Orix, which was fine for just me, but if you have luggage, you will need something bigger. This was a hybrid model with good fuel economy and a top speed of not very fast. This is fine though as speed limits on the Island are low, 40 kph in town, 50-60 kph on dual carriageways and a whopping 80 kph on the Expressway (about 50 mph).

After a while I found myself talking to the sat-nav in the car, as it takes absolutely ages to drive anywhere. The sat-nav had menus and screen options in Japanese, but with a neurotic English voice. I lost count of the times it said ‘excessive speed detected, please drive carefully’, ‘traffic joining from the left, please be careful’ and ‘please slow down, I’ve got a migraine’!
The real reason you need a car in Okinawa, is to visit the Hiji Waterfalls and Churaumi Aquarium. Sadly Hiji was closed when I got there, as last entrance is 3 pm up to the end of March, (4 pm April to September).
Churaumi Aquarium was once the biggest in the world, and is still pretty impressive today. It’s set in the Ocean EXPO park, which has lots to see including botanical gardens, dolphin pools, a kids playground, planetarium and great views of Ie Island. If you arrive after 4 pm tickets are cheaper, but I would suggest spending a day here, its that good.