John Hargrove can clearly recall the moment in 1980 when, as a wide-eyed six-year-old sitting with his family in the audience at a SeaWorld show in Orlando, he fell in love with killer whales. Harder to pinpoint is when his relationship with his dream job, training orcas for the theme park giant, finally turned sour.

It began with little things he says he started to notice about how SeaWorld treated its captive sea lions, dolphins and whales, and the trainers who would showcase them to the public. He says he saw cramped holding pools he believes were filled with too much chlorine; animals going blind or developing arthritis prematurely; and senior trainers banished from working with their beloved whales because they dared to speak out.

Later in his 14-year career, which is chronicled in his new book, Beneath the Surface: Killer Whales, SeaWorld, and the Truth Beyond Blackfish, he says he witnessed incidents that broke his heart: whales becoming aggressive towards trainers because of frustration at being confined in tiny pens for hours on end, or the anguished cries of whale calves forcibly separated from distressed mothers, against SeaWorld's stated policy.