Best food in Okinawa!!!
There is a salt factory on the way to to Ikei Island... I have no idea what the name was (maybe it was Yukishio), but there is only one salt factory in the area. Just ask around once you are in the area and you will find the place. The entrance is right off the main road. Definitely worth checking out. Just thinking about this restaurant makes my mouth water. I have lived in Okinawa for a total of 2 years, and this is the best food Okinawa has to offer (great desserts too).
The other "best food" is the Kobe tenderloin steak at the Four Seasons Steak and Lobster joint. There are 6 locations in Okinawa that I know of so it should be easy to find. I have to warn you that Kobe beef is a bit pricey, but I promise that you can taste the difference.
USO - Tunnel Rats Tour
Explore several caves that served as shelter during WWII and the Battle of Okinawa Historical Society museum. Keep a look out for old coins, rounds and other great finds.
Make sure you wear study shoes, a hat, flashlight/head lamp, gloves and old clothing.