I did a lot of research on this insurance question for our short domestic cruise in April, particularly the question as to whether it was covered by our credit card international travel insurance. The bank itself was useless on this but the insurer (Allianz) was thankfully very clear...
Please be advised that the PDS booklet defines ‘overseas’ as “outside of Australia and its territories and includes when you are aboard a foreign registered cruise vessel in Australian territorial waters”.
– this means that cruises ships with foreign registered vessel have provision for cover under the international travel insurance, which does have as a benefit international medical expenses.
Medicare will definitely not covered medical expenses on board so this coverage is welcome.