I agree with BR_Reef, there was some cargo on deck before, long cargo :-) You can still see the welded extra lashing point / D-rings on hatch 3

At a guess I suspect that the ship had discharged wind turbine blades at Portland before proceeding to Geelong and/or Melbourne.

Sorry but this is clearly some commercial promotional thing. The containers are on the ps hatches obstructing them from opening.
Cheers,
Roy

Simple answer to a " difficult " question.....
They must/will be loading cargo into the holds at their next port!
Regards,
Capt.Bill

All containers being the same would suggest this.
Some sort of promotional gimmick is the most likely explanation.
It looks pretty odd from the starboard side.

Odd way to have the containers loaded, I assume they are doing a promotional photo shoot at some point?