Anti-whaling campaigner Paul Watson, arrested Sunday in Frankfurt on a warrant from Costa Rica on charges relating to a high seas confrontation in 2002, has spent decades battling seal hunters.
The Canadian, 61, an early member of Greenpeace who also spent time with the merchant marine, devoted himself to saving marine life in 1977, forming the Earth Force Society, which later became the Sea Shepherd Conservation Society.
"Our goal is to protect the oceans because if they die, we will all die," he told AFP in a 2010 interview.
Born in Toronto in 1950, Watson says on his website that he carried out his first animal activism at the age of nine — setting out to confiscate and destroy animal traps.
But it was during a skirmish with Soviet whalers in 1975, in which he was stuck in an inflatable dinghy between hunters with harpoons and the whale pod, that he says developed his deep sympathy for whales.
In 1978 the Society bought its first ship, a British sea trawler, and renamed the vessel the Sea Shepherd.
"I happen to think that whales are more intelligent than people," he told the Sydney Morning Herald in 2010. "Certainly their languages are more complex and their communication skills are more complex."
"We put ourselves between a harpoon and a whale. They fired the harpoon over our head and hit a female from the pod. She screamed; it was like a woman screaming and there were fountains of blood," Watson told the Herald.
Just as another fatally wounded whale was about to attack Watson's dinghy, the giant animal caught his eye and changed its mind.
"As I looked up at that eye, rising out of the water, an eye the size of my fist; what I saw there really changed my life forever. Because I saw understanding. He understood what we were trying to do. I saw the muscles pull, and he pulled himself back and slipped under the sea to die."
The Sea Shepherd, which has increasingly clashed with Japanese whalers in the Southern Ocean, prides itself on "innovative direct-action tactics" to confront so-called "illegal" activity on the high seas — including the use of acoustic weapons, water cannon and stink bombs against whalers.
The not-for-profit group has also trailed seal hunters and fought campaigns for sharks and dolphins, as well as regularly patrolling the Galapagos Islands.
In 2010 it clashed violently with Japanese boats, leading to the sinking of Sea Shepherd's high-tech superboat boat Ady Gil in the remote Southern Ocean.
Despite its radical tactics, Sea Shepherd has garnered the support of Hollywood A-listers such as Sean Penn and French screen siren Brigitte Bardot along the way.
Benefactors include rock legend Mick Jagger, Red Hot Chili Peppers frontman Anthony Kiedis, surfing champion Kelly Slater, and actors Christian Bale and Edward Norton.
Watson, who claims in his biography to have co-founded Greenpeace but said he parted ways with the the group over arguments about protest tactics, told the Herald he loved the sea for the "total sense of freedom."
"You're out beyond the bounds of government control and you're one with nature, really," he said.