Many believe that huge unidentified monsters lurk in the world's oceans and waterways. Do remnants of the dinosaur age still exist, and is this what people are seeing off the coast of Wales in Britain and in San Francisco Bay in the USA? The Animal X - Natural Mystery Unit is on the hunt for Monsters of the Deep. Daniel and Natalie talk with eyewitnesses who have videotaped a pod of huge sea serpents. We have the videotape analyzed by an expert who says the tape is not a fake and the monsters are real. So much of the ocean is still unexplored. Could there be monsters we are yet to discover? Scientists answer 'yes - it's most likely', and they've even recorded sounds from the depths of the ocean that they can't explain. Have you heard of the Bloop? It's the sound of a huge underwater creature and is the biggest mystery in the ocean today.