Mr Latimer (26) was asleep on board the Sea Shepherd ship Bob Barker when Ady Gil lost its bow in a collision with the Japanese whaling ship Shonan Maru 2 last January.
During his first trip to Dunedin since the headline-grabbing incident, he yesterday said he was roused by the alarm - "a sinking vessel, there, I couldn't believe it" - and ran to the deck to see the badly damaged black trimaran in trouble in the icy water.
Mr Latimer had been sleeping in his warm protective clothing, and he and a navigator were the best equipped to immediately launch the inflatable rescue boat.
"It happened so quickly; there was a job to do and we just did it," he said as he scrolled through the photographs of the incident, at his parents' Waverley home.
"But you worry about the worst - I had no idea whether anyone was hurt or in the water."
The crew was safe and a relieved Mr Latimer ferried them to Bob Barker. A ship from the dispersed Japanese fleet watched as Mr Latimer returned to clean up the mess.
The cleanup took 22 hours - "we wanted to get every last bit; we're there to protect the environment, not pollute it" - but it did not stop the hunt for the whalers.
Less than a month later, Bob Barker got close enough to the whaling fleet's processing ship, Nisshin Maru, to stop it receiving whales from the rest of the whaling fleet.
The Japanese Whaling Association has called Sea Shepherd activists reckless and terrorists, but Mr Latimer said the claims were "pretty ridiculous".
"Yeah, we have been accused of breaking the law, but we have not been prosecuted - we probably use the same legal loopholes the whalers do.
"On the water, we do everything we can to be safe. We're really disciplined, and the guys that make the decisions aren't your regular Joe Bloggs sea captains.
"They're experienced; they know what they're doing; and after all these years they bring everyone home."
Mr Latimer was an electrician for Aotea Electrical in Dunedin when he left to work on Heron Island, on the Great Barrier Reef, where he was "converted" to conservation by the beautiful environment and its remarkable sea life.
He developed a strong interest in sharks and joined Sea Shepherd in March 2008, to help its shark conservation campaign - a campaign he expected to be waged in the warmer waters of South America.
Laughing off his unexpected South Seas experience - "if you'd rather not be there, there's something wrong" - he said he expected to volunteer in the engine room on many more Sea Shepherd campaigns after he rejoins his ship sometime next week.
"We know what we're doing ... is having a big effect on the Japanese whaling programme.
"One day, it'd be good to do an interview and say the job's finished, but as long as something needs to be done, I'll probably keep returning."
