Renata Rojas paddled behind her father through the water off the coast of Cozumel, Mexico. She was only five years old; never before had she been allowed out this far. Now, as she glided across the waves, her father stopped her and told her to look down to the sea floor. There, illuminated by the sunlight, was a sunken plane. She breathed through her snorkel as she studied its wings resting on the white sand.