Double demerits will be enforced by NSW Police from midnight on Friday, January 24 until 11.59pm on Monday, January 27.

Motorists caught speeding not wearing a seat belt or motorcycle helmet will also incur double demerits.

Commander of a highly-visible mobile policing operation for the long weekend, Assistant Commissioner Karen Webb, said there are many ways for the public to celebrate safely.

"Police recognise this has been a very difficult time for the community of NSW and we want everyone to have an enjoyable weekend celebrating everything that is great about being Australian," Assistant Commissioner Webb said.

"To ensure everyone enjoys the long weekend safely, police will be out in the community focusing on alcohol-related crime and anti-social behaviour.

"Anyone acting inappropriately will be dealt with swiftly and face the full force of the law.

"If you're planning on having a drink, remember the coveted national culture of 'mateship' - look after your mates and drink in moderation."

The police operation will extend onto waterways across the State through the marine area command.

According to marine area commander Acting Superintendent Joe Mcnulty, Australia Day is one of the busiest annual events on coastal waterways.

"With significant maritime traffic expected on the (Sydney) harbour and on waterways across the state, skippers are reminded that police will be conducting drug and alcohol testing on the water as well as compliance checks," he said.

"Before heading out on the water, check the vessel is in good working order, ensure all the required safety equipment is on board- most importantly, lifejackets.

"And remember the alcohol limit is 0.05 - just like on land - and with officers conducting random breath tests on the water, it's safer not to drink at all.

"Drinking alcohol or taking drugs while out on the water can end in tragedy, so look after your friends and family and act responsibly."