With friends like these, who needs enemies.
On face value, conservation groups Sea Shepherd and Greenpeace should have plenty in common. They both want to halt whaling in the Southern Ocean.
But the battle being waged between the groups is becoming more vicious than the more obvious war between them and the Japanese whalers.
"Greenpeace are the ocean poseurs ... I really have to question just what is Greenpeace's motivation in coming down here year after year," says anti-whaling activist Paul Watson from the Sea Shepherd Conservation Society.
Watson is strident in his criticisms of Greenpeace, an organisation he helped start decades ago.
The verbal grenades being lobbed are not all one-way. Greenpeace is also highly critical of Sea Shepherd.
"He (Watson) revels in being a pirate. He says he is prepared to defy the laws," says Greenpeace Australia's chief Steve Shallhorn.
While people in their loungerooms hear the debate over why Japan should cease whaling, another debate plays out in the Southern Ocean each year.
How far should activists go to stop Japan killing whales?
"We are absolutely aggressive," says Watson, who admits to sinking whaling and pirate fishing vessels.
His methods have included throwing foul smelling butyric acid aboard Japanese ships, and entangling their propellers with nets.
He has also sunk whaling ships in Iceland by ramming them, although he claims the vessels were always in port and no one was injured by his actions.
Last month two activists on his ship were held for three days after boarding a Japanese ship to deliver a protest letter.
Whalers call Sea Shepherd an "eco-terrorist organisation", the same way they refer to Greenpeace, and had threatened to take the captured men back to Japan to face piracy charges.
"Greenpeace always says Sea Shepherd is a violent organisation, but one of our big supporters is the Dalai Lama. He said to me 'you don't want to hurt anyone, but sometimes when they cannot see enlightenment you gotta scare the hell out of them until they do'," Watson said.
"That is one of the reasons we have adopted the pirate image. We like the image. It scares the opposition. We go after pretty violent people," he said.
He says that perception protects him from people including the "shark fin mafia" in Ecuador who he says have offered $US25,000 ($A28,000) to anyone who can kill him.
Shallhorn takes the opposite approach.
He says Greenpeace activists are kept safer because the organisation rules out violent confrontation and property damage, especially in areas where there is illegal logging.
"It is extremely important that governments and law enforcement agencies and loggers understand that Greenpeace is non-violent and does not do property damage," Shallhorn says.
"Occasionally I do speak to senior police officers and military officers, and they get it. People understand the difference between protest and criminality. It is very important for us to not blur that image," he says.
He rejects Watson's claims that his organisation uses its protests in the Southern Ocean mainly to generate publicity for the group.
"It is simply not true. We go there to stop whales being killed."
Shallhorn also says Greenpeace is trying hard to spark debate in Japan over whaling, a strategy having some success.
"The Japan battleground will be the decisive one to get them out of the Southern Ocean. We think if there is an active public debate in Japan, we can win it," he said.
But Shallhorn said Sea Shepherd's brand of activism could be a good thing for the environment movement.
"I think they represent the fringe of the environmental movement, but that fringe does exist. In some ways Sea Shepherd provides a voice for that fringe," he said.
Despite this Greenpeace has chosen not to share its coordinates of the Japanese whaling fleet with Sea Shepherd, much to Watson's annoyance.
"They are quite a different organisation in almost every respect," Shallhorn says.
