Oura Bay on the east coast of Nago, northern Okinawa, packs sand flats, mud bottoms, coral reefs, seagrass beds and a deep valley into one small area, making it one of Okinawa's richest marine habitats. It is home to one of the world's largest blue coral communities, which you can see by diving, snorkeling or glass-bottom boat. This guide covers the highlights, boat tours and access.