"This small island located off the Joyuda coast in Cabo Rojo, is open to the public under the supervision of the Department of Natural and Environmental Resources. The name “Mouse Island" derives from its size, not because of mice."
Picture from vantage point of Joyuda beach:
This is a great map which also shows the location of "Ratones":
And a mislabeled photo, I think (although the island IS near Laguna Joyuda):