The quadrennial event is the most important on the calendar this year for those eligible with action taking place at the Tobruk Memorial Pool until August 13.

Hosts Australia will be joined by swimmers from United States, Canada, Japan, Brazil, Costa Rica, India, New Zealand, Singapore and South Africa.

Six of the Rio winners will represent the home team, including double champions Lakeisha Patterson and Ellie Cole.

"The Para Pan Pacs mark the halfway point of our cycle and is an important step on the way to Tokyo 2020," said Swimming Australia's Paralympic high performance manager Adam Pine. 

"It's been two years since our team performed in Rio and we have some new faces and developed stars.

"With high performing athletes from USA, Brazil, Japan, New Zealand and Canada competing, the bar is set high and it's a great opportunity for our team to practice and hone our racing skills."

The event is run with multi-class heats and single or combined class finals.

Triple Rio champion Aurelie Rivard will be one to watch for Canada.

"For me it's no different than the World Championships," she said.

"The preparation is the same as if I'm heading into the Worlds.

"I just want to be better than what I was the previous year. 

"I like winning. 

"That's what I’m looking forward too."

The US will feature Paralympic and world champions Rebecca Meyers, McKenzie Coan and Jessica Long while Brazil's 14-time Paralympic gold medallist Daniel Diaz will be the star of their squad.

Keiichi Kimura, a six-time Paralympic champion, will be a threat for Japan, with Sophie Pascoe and Cameron Leslie - both Rio winners - included in the New Zealand ranks.

Leslie is currently playing with the Kiwis at the ongoing Wheelchair Rugby World Championship in Sydney.