How is it like?
Okinawa is the southernmost prefecture of Japan and is a group of 160 islands. When people say Okinawa, it normally means Okinawa (main) island which is the biggest island of Okinawa and its capital is Naha.
Okinawa island is long from south to north (about 110km/70ml) but narrow from east to west.
Okinawa is a tropical island and air temperature gets 32-33C/90F in summer and 15-16C/60F in winter, water teperature goes up to 30C/85F and barely goes below 20C/70F even in winter.
Diving is very big here. Only in Okinawa main island, there are over 50 dive sites.