New Zealanders have long scoffed at suggestions of becoming Australia's seventh state but in a major shock on both sides of the Tasman, it turns out Kiwis and Kangaroos once could have got along fine if only the terra nullius had stayed united.

But about 75 million years ago, a mass of land broke away from Australia and started drifting east before subsiding beneath the sea.

Now an expedition led by the Australian National University will make the first scientific efforts to try to solve the mysteries of the underwater continent that was believed by some to have been discovered and named Zealandia just 22 years ago.

The drill ship JOIDES Resolution leaves Townsville on Friday for a two-month research voyage with up to 55 scientists on board.