Mysterious land formations in Peurto Rico. Hi While planning my vacation I came across this feature on the northeastern tip of Vieques island Puerto Rico. It happens that there are two of these shapes the other is closer to the tip of the island and it seems that the underlying limestone bedrock acccentuates it even more. Do you know what they are? The US had a large naval base for many years on the island that they recently abandoned but they don't look like modern structures. What could these be? Edwin Vazquez Back to Viewzone || Comments?