The Sea Shepherds draw a clear line between property destruction and physical violence and there are few that would argue against their commitment to enforcing international environmental laws, yet their methods put them at the centre of much controversy. A run in with the group may be very costly, as when they sank half the Spanish whaling fleet, but they have never been convicted of a crime. Their actions have not caused injuries but are effective at stopping those who break the law.

Paul Watson co-founded Green Peace in 1972, leaving the organisation 1977 because he felt its original goals were compromised. That same year he started Sea Shepherds to continue direct action tactics to defend marine wildlife. He is professor of Ecology at Pasadena College of Design and also teaches ecology at UCLA. He is author of Sea Shepherd: My Fight for Whales and Seals and Ocean Warrior: My Battle to End the Illegal Slaughter on the High Seas.