I recently read my cover-more policy as issued by Commonwealth bank.
Here is what it states
"Cruising in Australian waters
Cover is included under Overseas Medical, Benefit 2: Overseas Emergency Medical and Hospital Expenses if you are travelling on a domestic cruise in Australian waters.
When you complete the steps to access the Overseas Travel Policy, for a domestic cruise, not part of an international journey, please choose ‘Pacific’ as your destination."
So it looks like this one does cover domestic cruise.
As always, best reading the PDS in detail to check specific coverage