The Canberra high school student died after a boat carrying six people capsized off the Moruya bar in "awful" conditions early on Saturday morning.

NSW police acting superintendent Darren Wood said she was found under the hull of the boat about 40 minutes after the vessel capsized.

The ACT government expressed its "deepest sympathies" to the family and friends impacted by the tragedy.

"The ACT government wishes to convey its deepest sympathies to Georgia Vizovitis' family and friends, and to the Mt Stromlo High School community at this difficult time," a government spokeswoman said on Sunday.

Lifesaver Andrew Edmunds said Moruya and Batemans Bay crew members helped bring people ashore after the boat capsized crossing the bar early on Saturday morning.

"Conditions were awful," he said.

"Our hearts go out to the family and the people involved.

"The conditions today were absolutely awful – there was a two-to-2.5 metre swell, a very strong outgoing tide and, even for us, with trained personnel in big surf, it was challenging."

Mr Edmunds said the crews had done their very best, but could not save the teen.

"They did a tremendous job," he said.

"CPR was conducted as they returned to shore, but unfortunately she was not able to be revived."

He said a trio from another civilian boat initially helped the stricken party in very difficult conditions. It is understood the boaters were taken aboard the other vessel until rescue crews arrived.

Surf Life Saving NSW responded to reports of a capsized vessel just before 7am on Saturday.

Crews from Moruya and Broulee rescued five people from the overturned boat.

"It was a very distressing scene, a very traumatic incident," a Surf Life Saving NSW spokesman said.

NSW Ambulance and NSW Police also responded to the incident.

"We have a total number of five patients, all of them were transported to Moruya Hospital," a NSW Ambulance spokesperson said.

They suffered minor injuries, including suspected hypothermia.

The girl was one of six on board the boat, including two other children also aged 13, and three men aged 18, 29 and 46.

NSW Police acting superintendent Wood said the passengers were from the ACT and Victoria, and were family friends. 

"They were heading out for a day's fishing to a known fishing spot," acting superintendent Wood said. 

"Other vessels in the area raised the alarm. 

"It's heartbreaking," he said.

"Crossing the bar on an outgoing tide is always the most difficult. The waves become steeper on an outgoing tide and closer together, it is the most difficult time to cross.

"You must be wearing a life jacket when you cross a coastal bar," he said.

He said reports of hazardous surf will be a factor in the ongoing investigation.

A report will be prepared for the Coroner.