Thomas Cox 
Treasure of Shark’s Reef [EPUB ebook] 

Ramon Sanchez and his girlfriend, K.C. Roth, find adventure and danger as they try to rescue K.C.’s friend from an overextended deep-water dive into a ship’s graveyard. Legend has it that the sunken vessels are protected by a "ghost shark." Ramon and K.C. already had discovered a large shark in the area. A further danger is the fact that the diving companions are criminals seeking a treasure in illicit drugs in the same location. As they descend into dark, risk-laden waters, the kids face two imminent threats: the monster shark and two dangerous men who will use anyone and stop at nothing to achieve their goal.