アーヂ島 adji-jima (or aadji-jima) in a very tiny island located off the Nanjo coast of Okinawa main island. The name means “hideout.”
As you drive down towards it, you come to a tori gate 鳥居 utility pole… interesting. You can park in an area off to the side of the driving path (I call it a path, because it is really not much of a road). There is a concrete bridge connecting Adji-jima to land. You can walk across but…
It is gated off at the entrance to the island. It is actually a private property, possibly owned by a resort from the 80s and is said to have been a training facility for the resort, but now… no one seems to be sure of ownership from what I have read. It seems well-kept enough, so I don’t think it is abandoned. It is a bit mysterious.
Since you cannot enter, you can walk (at low tide) or wade (during high tide) circling small “island”. It is surrounded by barbed wire fence on the land. There is even a marker for 1983 when it the facilities were made. You can see some various structures and such too. There even seem to be some sort of dock for a boat, but the water must be too shallow for this to be used. It is a bit strange overall. Perhaps the strangest is that there is a sign on the main road for this hideout island even though you cannot enter and it is privately owned. It is close to Hyakuna Beach 百名ビーチ though, so you could just walk over from here and enjoy some beach time.