"I slid for 50 metres down the cliff ... I was airborne a couple of times, due to how steep it was."
Mr Italia tried to grab one of the few trees on the way down but couldn't hold on. Instead, he kept sliding towards a 20-metre drop, just managing to grab the last tree, which was jutting out on a 45-degree angle over the edge of the cliff.
"I hit it and wrapped my body around it and just ... held on. I looked over the edge and there was a 20-metre drop to solid rocks and water.
"If I didn't grab that tree I would have died."
Mr Italia clung on for about 20 minutes before realising he needed to do something or "might not make it".
"I couldn't climb so I had to get my knife out and dig [foot]holes into the ground and grab on to tree roots or ... solid rock that wouldn't fall out."
It was slow going and took about an hour to climb just 15m in the steep shingle - a journey made even harder by his injuries.
By 6pm, with darkness setting in, Mr Italia reached a slight rock shelf with another tree which he climbed on to as it was getting too dangerous to keep going.
"I held myself on to the tree, put a [survival] blanket around myself and tied my LED lamp on to the tree pointing into the other valley.
"I just stayed there the whole night trying not to fall."
It rained heavily during the night and got very cold so he used a lighter to try to heat his hands. His only food was half a packet of barley sugars.
"It was the longest night of my life. I was just waiting for the light and it wouldn't come up," Mr Italia said.
At daybreak, he continued his climb, which took another three hours, and then made his way down the stream, retrieved his rifle - which he had dropped during his fall - and let off three shots for help.
With no response, he made his way back to Hanamahihi Hut, on the Whakatane River, where his uncle's friend was waiting anxiously.
His uncle, Wayne Baird, had already flown out - on the chopper that was supposed to collect the three of them - to organise a search party after failing to find him that morning.
Mr Baird said he knew something was wrong as soon as his nephew failed to return to the hut that night.
"The last thing you want to do is tell your sister you've lost her boy."
Mr Italia said it was "awesome" knowing he had made it back alive.