Stockton Surf Life Saving Club president Callan Nickerson said a record number of competitors were expected to take part in the annual swim, lured by more than $3500 in prize money.

The annual swim is the surf club's largest fundraiser and will be sponsored next year by the City of Newcastle and Port Waratah Coal Services.

Mr Nickerson said the swim raised much needed funds for the club's vital surf life saving activities.

"It means we can deliver a high quality event and importantly raise vital funds for our surf patrols and lifesaving operations at Stockton Beach," Mr Nickerson said.

"The great prize money on offer makes the Newcastle Harbour Swim the richest open water swim in Australia."

The event will feature a single crossing of the harbour, or 700 metre swim, starting at 10am.

The double crossing of 1400 metres starts at 11am. The double crossing boasts a cash prize of $3500 split across male and female podium finishers.

Once a year keen swimmers are legally allowed to swim across the world's largest coal port from Stockton to Newcastle, when the harbour master gives the surf club the all-clear to start the race.

Newcastle-bred Olympic swimmers Thomas Fraser-Holmes and Justin Norris are both previous winners. For more information or to register, visit oceanswims.com