The Black Pearl (Scott O'Dell)
The story is about a Mexican teenager named Ramon Salazar who works with his father finding and selling pearls. One day, Ramon went diving in an underwater cave in search of pearls and found a pearl bigger than his fist. It was so shiny and big that he thought that it was called the Pearl of Heaven. The pearl was found in a lagoon that belonged to an Indian who warned Ramon that the pearl belonged to the Manta Diablo.