Anti-whaling activists are taking their fight close to the Japanese coastline.
The Sea Shephard group will for the first time try to stop Japan's whaling fleet soon after it leaves its Japanese port.
Spokeswoman, Anna Kingston, says four of the group's ships will intercept a Japanese factory ship and a harpoon ship heading to the Southern Ocean of Japan's summer whaling season.
"They've already left on their campaign and they've headed towards Japan," she said.
"We're going to try to cut off the factory ship and the harpoon ship in northern waters before they reach Antarctic waters this year."
In previous whaling seasons, Sea Shepherd has made statements to the media as a decoy.
One season, the group said it would journey north to head off the Japanese ships before they reached Antarctica, prompting Japanese coastguard vessels to assist the whaling ships to leave the port.
The group's ships instead waited for the Japanese boats closer to the Southern Ocean Whale Sanctuary.
Earlier this month, Sea Shepherd founder Paul Watson, who is wanted by Interpol, confirmed he was back onboard one of the group's boats and ready to confront Japanese whalers.
The Canadian conservationist's whereabouts had been a mystery since July when he jumped bail in Germany, where he was arrested on charges stemming from a high-seas confrontation over shark finning in 2002.
Sea Shepherd had said the captain would be involved in this season's campaign against Japan's whaling operations and he has confirmed that he is back in charge.