The killer whale is one of the most feared predators in the ocean and most would consider it madness to enter the water with one.
However, New Zealander Dr. Ingrid Visser is undaunted by their reputation - she is "the woman who swims with killer whales".
By actually getting in the water and swimming with her beloved orcas she has come to know almost all of them by sight and has witnessed some remarkable sights.
Killer whales are one of the most wide-spread mammals on the planet, inhabiting every ocean on Earth. They have a varied diet, linked uniquely to their individual habitat, and display incredibly complex social behaviours.
Recently, there have been an unusual number of deaths involving killer whales and this has sparked Ingrid to set out in her mission to find out what is going on. Her study reveals disturbing new information about the health and well-being of our oceans.