The moment that rescue divers Rick Stanton and John Volanthen found 12 Thai schoolboys and their soccer coach after nearly 10 days in a flooded cave is difficult to forget. “How many are you?” Mr. Stanton said, waving a flashlight toward the bedraggled, hungry boys. “13? Brilliant!” It was the latest in a long series of rescue missions undertaken by the British duo, widely regarded as among a select few cave divers with the necessary skills and experience to find a path to youngsters cut off deep inside. “They are the best in the business,” said another diver