Oryukdo Islets

This guide to the Oryukdo Islets in Busan opens with a centuries-old argument that even an eighteenth-century Korean geography text couldn't settle: are there five islands here, or six. It shows how the tide itself is the culprit, splitting the nearest islet into two separate humps as the water rises, and traces the stone's origin back roughly eighty million years to volcanic ash and lava, shaped by something like a hundred twenty thousand years of erosion. Deungdaeseom, the farthest islet, still does useful work, its lighthouse guiding ships into Busan's harbor.