Watch Natural World Season 27 Episode 15 Online

The billfish are the biggest, fastest, and most dangerous gamefish in the sea. All have captured man's imagination like few other creatures, whether it's the graceful sailfish, the menacing swordfish or queen of them all, the marlin, immortalized by Hemingway in 'The Old Man and the Sea'. Marine biologist and film-maker Rick Rosenthal has travelled three oceans in his attempt to capture them all on film, and in doing so has become a passionate champion for these endangered yet little-known ocean giants.