Matt Canavan, Colin Boyce and Michelle Landry say central Queensland should be considered as a new submarine base due to its northern location.

The shortlist for an east coast base includes Brisbane, Newcastle and Wollongong.

But Senator Canavan is adamant Gladstone is Australia's second-best harbour, only behind Sydney.

"It's an ideal location. We've got the world's best marine military training facility, we're a hub for transport links and we have an airport that can land all but the biggest aircraft," he said.

"It's north facing. If we are to face any threat to our nation, it is more likely to be from the people to the north than the penguins from the south."

He said it made no sense there wasn't a permanent military presence in the region.

The senator said local councils had engaged defence and economic consultants to prepare a report about why a naval base in central Queensland stacks up.

"About $30 million a year is spent just transporting the tanks from Brisbane to central Queensland, up and down the highway," Senator Canavan said.

Australia isn't set to acquire its first nuclear submarine through the AUKUS pact with the US and UK until the early 2030s.

Defence Minister Richard Marles says it's an important step for the nation.

He also played down reports Labor MPs had voiced concerns about the pact, saying he's answered lots of respectful questions about the decision.

"That's what you would expect, this is a huge decision for the country," he said.

"As I go around (parliament), there is a huge sense of unity about the need for us to acquire this capability because this is what will allow us to hand to our kids and our grandkids a much more self-reliant nation."