Halpin was chosen by Tors for the role of Sandy Ricks because of his skills in the water as well as his extensive prior acting experience. He also proved able to bond quickly with the dolphins who filled the role of Flipper. This chemistry paved the way for the launching of the TV series after the two feature films. By the time filming of the TV series commenced, Halpin had become an expert skin and scuba diver and exhibited an easy athleticism that enabled him to perform many of his own stunts in and below the water including a number of dangerous scenes involving sharks. His popular TV character became defined by many water-activity related plots with him often wearing nothing more than what came to be his signature cut-off blue jeans shorts.