An entire Australian family died due to the volcanic eruption.
Barbara Hollander, 49, and Martin Hollander, 48, were visiting Whakaari/White Island with their two sons when it blew.
Berend Hollander, 16, and Matthew Hollander, 13, were US citizens with Australian permanent residency like their mother. Matthew is the youngest victim on the official White Island eruption death toll.
Both boys attended Knox Grammar School in Wahroonga, on Sydney's North Shore, where their father had gone to school before them.
After the two teenagers died in hospital the Hollander family released a statement saying they were "absolutely heartbroken" by the loss.
"Ben and Matthew were wonderfully kind and spirited boys who lived short but very fulsome lives."
The boys had loved their school, Australian sport and an outdoor lifestyle, the statement said.
"They had a positive and lasting impact on everyone's paths they crossed."
"He was a really devoted dad and the best husband to my mum."
Cozad was travelling with wife Bianca and family on the Ovation of the Seas cruise ship as they were celebrating their 20th wedding anniversary.
On December 9 he decided to take the tour of Whakaari / White Island, leaving Bianca and his two younger daughters and other family members behind on the ship.
Australian couple Karla Mathews, Richard Elzer and friend Jason Griffiths
Three Australians from Coffs Harbour, Jason Griffiths, 33, Karla Mathews, 32 and her partner Richard Elzer had been holidaying with a group of friends on the Royal Caribbean Ovation of the Seas cruise ship.
NZ Police said on Sunday that Mathews was among those killed, but her death, as well as those of Elzer and Griffiths, had already been confirmed by friends.
"On the 9th of December 2019, we were devastated by the news that three of our friends were visiting White Island on a shore excursion during the time of eruption," a joint statement issued by friends and the Australian Department of Foreign Affairs and Trade said.
"Some time later, we discovered that two of our friends, Richard Elzer and Karla Mathews, were still on the island.
"We then located our third friend, Jason Griffiths, in a hospital in the early hours of the next morning.
Young White Island tour guide Jake Milbank suffered burns to 80 per cent of his body and is now in Middlemore Hospital's intensive care unit.
A family friend described him as passionate about nature and all living creatures, especially everything in the sea as he and his father spend a lot of time together out there.
"He is a very kind boy with a huge heart," she said.
"We want to do what we can in order to ease the burden of their recovery.
"Any money raised from this campaign will be given directly to Matt and Lauren in order to cover expenses resulting from this disaster for themselves and their family."
As at 4pm on December 16, more than $34,000 had been raised.
Marion and Nick London
Australian media reported Marion and Nick London, from Engadine in southern Sydney, were hospitalised following the eruption.