Minamijima is the boat-trip image of Ogasawara: an uninhabited limestone island with a pale sand cove, a natural sea arch, and clear blue water inside the lagoon. It is fragile as well as beautiful, so visits are controlled and usually require a licensed guide.
The best trips combine Minamijima with dolphin watching or snorkelling around the south of Chichijima. Conditions matter. Rough seas can cancel landings, and visitor numbers may be limited to protect the island's plants and nesting birds.