It is a little island off the bottom of Vietnam called Hon Son or Lại Sơn depending who you ask.
It is 12 square kilometers and 16 kilometers to ride around the perimeter.
Very nice! I was born three days after the fall of Saigon and fled Saigon three years later. I haven’t been home since but my wife and I are planning a diving trip there soon. This will also give us the opportunity to take our son to see part of his heritage 😀