A Sydney teenager has been left with a fractured skull and possible brain damage after emergency services again experienced a New Year's Eve marred by violence and drunken antics.
Preliminary figures showed around two million people came into Sydney to watch the $6.8 million firework display on the harbour, well over the expected crowd of 1.6 million.
While the majority of partygoers had a safe and happy night, emergency services bemoaned the violence that continues to accompany the night.
As the first fireworks display showered over Sydney Harbour at 9pm, 18-year-old Daniel Christie was knocked to the ground in an unprovoked attack at Kings Cross, police say.
He was rushed to St Vincent's Hospital where he remains in a critical condition.
When his alleged attacker, Shaun McNeil, 25, fronted Parramatta Bail Court on Wednesday, it heard Mr Christie was shielding others when he was allegedly struck by McNeil.
Police Prosecutor Sergeant Lisa McEvoy said McNeil was celebrating in the city from 9am and had consumed around nine drinks.
He has been charged with one count of causing grievous bodily harm to Mr Christie, one count of assaulting Mr Christie's brother, Peter Christie, and two counts of common assault.
"At the end of his time in town, there's a man on the floor with a fractured skull and suspected brain injury and other people with cut lips," Sgt McEvoy said.
Facts tendered to court stated that Mr Christie had undergone emergency neurological surgery to repair fractures to the skull and bleeding on the brain.
"(He) is currently critical and is likely to suffer considerable brain injury as the best case diagnosis," the facts state.
The attack occurred on the same street where teenage king hit victim Thomas Kelly was killed in 2012.
McNeil was refused bail to appear in court next week.
NSW Ambulance Deputy Commissioner Mick Willis said paramedics and St Johns Ambulance staff treated more than 1000 patients throughout the metropolitan region overnight.
"Overall the crowd was very good ... but sadly again through the use of alcohol and drugs we saw a number of violent clashes," he told reporters in Sydney.
In one incident in Wollongong, a paramedic treating a man was allegedly assaulted by bystanders.
Meanwhile just after midnight in Marrickville in Sydney's inner west a 20-year-old was treated for head wounds and a fractured wrist after he fell 10 metres from a balcony.
Elsewhere in the city, drama struck when more than 100 New Year's Eve revellers were rescued from sinking boats across the harbour.
Three people were taken to hospital - one unconscious and in a serious condition - after their boat sank on the harbour at 9.40pm (AEDT).
Overall, more than 170 people were arrested across the state and charged with 222 offences including assaults, robberies and drug offences.
While arrests were up from last year, Acting Police Commissioner David Hudson said that given the increase in crowd numbers it was not a bad result.
"We are never going to see an incident free New Year's Eve no matter how many police we put out there and how many pieces of legislation we enact," he told reporters.
