Sable Island, Nova Scotia, is a remote, almost mythical landscape in the northwest Atlantic that's famous for its wild horses. But what many people don't know is that it's also home to the largest breeding colony of grey seals in the world. Every winter, tens of thousands of female seals head to Sable to give birth. In 2016 alone, more than 80,000 pups were born. Huge males arrive too, ready to fight for the right to breed with their chosen female.