How formal is formal on South Pacific cruises?

[Gwendy]

No difference to other cruises, Mediterranean in April, no one in true formal gear, just slacks and dressy tops for some, others just anything goes.  Greenland last month, same.  Some people make an effort, some wear tshirts and cargo pants, even saw someone with a baseball cap worn backwards in dining room on formal night.  Not even a sparkly cap.  Lol

[PescadoAmarillo]

We found cruises round trip from Australia or New Zealand to be rather informal except for holiday periods. Aussies and Kiwis are laid back and friendly, my favorite cruisers.