The anti-whaling activist, Pete Bethune, says it is unjust he has spent time locked up, while the whalers who collided with his vessel have not been held accountable.
Bethune arrived back in New Zealand on Saturday morning. He was deported by Japan after a Tokyo court gave him a two-year suspended sentence.
He returned to New Zealand on Saturday after being deported from Japan, where he'd been in jail since his arrest in February. He had on Wednesday received a two-year suspended jail sentence on five charges relating to illegally boarding a whaling ship.
The activist is hugely relieved to be home, but says justice has not been served in relation to the whalers.
He hasn't ruled out going back to Antarctica but says he needs to talk to the Sea Shepherd group before he decides what to do next.
Bethune has compared the sinking of his speedboat Ady Gil to that of the nuclear protest ship Rainbow Warrior, which was sunk by French saboteurs in Auckland harbour 25 years ago on Saturday.
Bethune says he hopes the incident, which triggered his boarding of a Japanese whaling vessel, may encourage further protest efforts.
Bethune weeps on arrival in Auckland
At Auckland Airport, a tearful Bethune said he had been worried he would be sentenced to a prison term. The 45-year-old said the final month in prison while awaiting trial started to grind him down.
"You're not allowed to talk to any other prisoners, you're not allowed to talk to any guards unless they speak to you, and it just drives you nuts."
He said he had no complaints about the way he was treated in Japan, but he does object that Japan has been "so poor at pursuing the criminal acts of the whalers".
Bethune is calling on the New Zealand Government to take a stronger stand against illegal whaling, saying New Zealand in the past used to stand up to other countries about big issues.
He was reunited with his wife and two daughters at the airport where friends, several supporters, including the Green MP Keith Locke, and an international media contingent had also turned out.
Wife Sharyn Bethune said it had been a roller coaster of emotions, especially during the sentencing, when they thought for a time he wasn't coming back.
"We'll get him home and try and keep him in New Zealand for a while, I think," she said.
Ady Gil destroyed in collision with Japanese whaler
The 45-year-old was the captain of the powerboat the Ady Gil, which was cut in two in a collision with the Japanese fleet's security ship Shonan Maru II on 6 January in the Southern Ocean. It sank soon afterwards.
On 11 February, Bethune boarded a Japanese whaling vessel and attempted to make a citizen's arrest of its captain and hand over a bill for the loss of the Ady Gil.
A Tokyo court on Wednesday found him guilty of five charges related to boarding the vessel.
He admitted four charges, including vandalism and carrying a knife, but denied a charge of assault.
In Tokyo, immigration officials had escorted Bethune from a bus to the plane, as Japanese media tried to photograph him from a distance, the ABC reported.