Mr Lawrence was staying in a Wellington motel when the unusual noise woke him about 6am.
He said he discovered his two-week old iPhone self-destructing.
"I was lying in bed, I’d just woken up and I was like, ‘what’s that hissing noise?’
"I noticed it was coming from my bag, so I jumped up, unzipped the bag and then smoke poured out of the bag.
"It was crackling and hissing and bubbling, then the whole back of it started to melt, so I picked up the whole thing and took it outside.
"Just the smoke alone was intense."
A cancelled ferry the day before had forced Mr Lawrence to stay in the capital.
He was due to board another ferry in less than two hours when the fire started.
He had taken advantage of the unexpected layover to have the phone’s screen, which had been damaged from a fall, replaced the day before.
Mr Lawrence said Apple told him it planned to escalate the event to its safety team.
"If I hadn’t have woken up ... I could’ve got smoke asphyxiation."
Had he already boarded the ferry, the phone would have remained in his bag inside his car — the fire would have gone undetected and could have had serious consequences, he said.
Interislander fleet operations manager Taru Sawhney said the ferry service had a comprehensive plan in place and vehicle decks were continuously monitored with a fire detection system and CCTV for early detection and response.
"If a fire started in a vehicle on our vehicle deck, our highly trained crew would follow established emergency procedures, which include sounding alarms, commencing mustering protocols, immediately using on-board fixed fire suppression [drencher] systems, isolating ventilation and electrical systems and using fire resistant barriers built into the vessel’s structure to prevent the fire from spreading."
The ferries were equipped with a mix of firefighting tools designed for different types of fires — including battery fires, he said.
