It could signal the start of a bold new way to commute between Canberra and Sydney.

The National Capital Authority has approved the demonstration flight on Tuesday to test the viability of a route between the two capitals.

Sydney Seaplanes came to the authority with the proposal in January, offering three daily services.

The plane arriving on Tuesday will carry 10 passengers, and there is scope for a bigger vessel seating 15 if there is enough demand.

Authority chairman Terry Weber said the potential route would link "two water icons" in Sydney Harbour and Lake Burley Griffin.

If they take off, the flights would leave from Rose Bay and take about an hour to arrive in the capital.

A ticket would set you back about $300 each way.

Mr Weber said the trial flight on Tuesday would allow the authority to determine whether it could be done safely for passengers and the environment.

The notion of a seaplane landing on the lake has been raised in the past but never eventuated.

Authority chief executive Sally Barnes said "the regulatory path seems clear" but work would need to be done after Tuesday's flight in consulting with the community and understanding any environmental impacts of regular landings.

"It's now really up to NCA and whether we're happy to have them on the lake, and that's what we're going to be looking at and testing at the demonstration," she said.

"After the demonstration we need to work through things like ... where they land, how the passengers get on and off safely, where they might refuel."

Regular arrivals could begin from late next year if the plan gets the tick of approval.

"Which is terrific for post-COVID recovery, to have a new product in third quarter of 2021 would be just perfect," Ms Barnes said.

Mr Weber said the new way to commute could be a boost for tourism and business, with the industry eyeing a return to large-scale events by the end of next year.

"The planes will eventually hold about 15 people ... taking off from Rose Bay and landing at Lake Burley Griffin you avoid a lot of traffic," he said.

"It could well cut down travel time significantly."

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