Skipper Rewai Karetai set off from Bluff about 8pm with eight members of his extended family - the youngest just 7 years old.
Four hours later a massive wave hit the vessel, causing it to capsize. The only survivor was Dallas Reedy, who endured a harrowing 18-hour ordeal in the icy southern waters.
MetService spokesman Dan Corbett said the water temperature in the strait at the moment was about 14C. It is thought a person could survive in water that cold for up to six hours - or for as little as 60minutes.
Mr Reedy said a freak wave caused the vessel to go down. Also known as rogue or killer waves, these are spontaneous and occur far out at sea.
They happen where physical factors such as high winds and strong currents cause waves to merge to create a single exceptionally large wave.
Mr Corbett said the sea would have been very rough and while 4m swells had been predicted, he expected them to be much higher.
Mr Reedy was not wearing a lifejacket when rescued, police said. He survived by clinging to a barrel.
Police confirmed that the first body found, that of Shane Topi, was also without a lifejacket. Two more bodies were found yesterday but police did not disclose whether they were wearing lifejackets.
Speculation was also rife about the condition of the Easy Rider and whether it was seaworthy enough to make the trip.
Former oyster fisherman Christian Fife said the vessel was overloaded when it left port.
"This is going to be a s*** storm," Mr Fife said. "She [the Easy Rider] was full of gear. She was overloaded ... the arse was in the water at the port."
A man who runs fishing charters from Bluff also had concerns.
"I saw the boat before it left. Personally, I wouldn't have gone out in it. It had a fair load aboard ... they probably shouldn't have gone. And it was pretty atrocious conditions."
It was also revealed yesterday that the vessel had sunk at least once in the past - before Mr Karetai owned it.
The boat spent years in Westport, where it sunk in its berth after years of neglect. Westport harbourmaster Nico Weeda said it sank a second time about two years ago shortly after taking on water, again while berthed.
It was not known what repairs Mr Karetai had done since he bought the boat. But locals said he was a good fisherman and he well respected in the community for it.
Coastguard boating education service manager Neil Murray said it was crucial for skippers to check the latest marine forecasts before hitting the water.
All equipment needed to be thoroughly checked before setting off, including lifejackets. Skippers must make sure there were enough for everyone on board and that they were the right fit for adults and any children.
Mr Murray said having at least two forms of emergency communication was also essential - either a marine radio, cellphone in a waterproof bag, a beacon or a flare.
Taken by the sea
Shane Ronald Topi, 29
(Confirmed dead yesterday)
Originally from Greymouth, Shane went to Cargill High School in Invercargill and was working as a crewman on the Easy Rider. It is the second sea tragedy for the Topi family, who lost a number of relatives including Shane's cousin Peter when the Kotuku sank in Foveaux Strait. It is understood Shane could not swim and did not like water. He was described yesterday by friends as a big, happy guy with a heart of gold. He was also very close to his family. Shane also worked part time as a bouncer and was loved by his workmates.
William Rewai Desmond Karetai, 47
The skipper of the Easy Rider and known to friends and family as Spud, Rewai works as a fisherman and is from Dunedin but lives in Mataura. He was hailed a hero in January when he towed three people to safety in his one-man dinghy after their vessel capsized in Foveaux Strait. Rewai rowed out in darkness off an island where he was camping to rescue Southland farm manager Barry Bethune and two women who spent more than five hours in the icy water.
Boe Taikawa Gillies, 28
Boe was looking forward to the muttonbirding trip and told friends he was excited. In his late 20s, Boe loved tattooing and rap music and had many friends around his hometown of Invercargill. One of seven children, he was described by one of his sisters yesterday as the family's baby gentle giant. He had no children but is survived by 11 nieces and nephews. Tributes were flowing for him yesterday, including one from a friend begging him to "come home". "Invercargill knows all of you and will never be the same again without you guys."
Odin Karetai, 7
Odin was the youngest victim of the Easy Rider sinking. He was a loved son of Cora Maere, who said she was so proud watching him perform in a kapa haka group last year that she almost cried. He is survived by several siblings.
Paul Jason Fowler-Karetai, 40
An engineer, Paul was the father of Odin Karetai and the partner of Cora Maere, with whom he had other children.
David George Fowler, 50
A former player for the Panthers Rugby League Club in Southland.
John Henry Karetai, 58
Peter Glen Pekamu-Bloxham, 53
Four bodies had been recovered last night but only one had been identified.
Treasured catch
Muttonbirds, or sooty shearwaters, are known to Maori as titi. These seabirds, according to one 18th-century commentator, taste remarkably like sheep meat.
Muttonbirds are harvested by Rakiura (Stewart Island) Maori, from the southernmost region of New Zealand.
Their cultural legacy includes travelling once a year to the 36 islands around the southern tip of the country, where the birds are a prized catch.
Source: Te Ara, The Encyclopaedia of New Zealand
