Vanuatu to Brisbane, What's This Stuff?

Position 18 06.933S 166 07.554E
Day 2 of our passage from Vanuatu to Brisbane.
Wind dropped last night around midnight. We have been motoring since. Weather forecast is for light winds for the next 36 hours. The sun is shining, we have moon light at night, full moon is Saturday, and calm seas. The winds are forecast to pick up in a couple of days.
We are traveling with Onda, The Road, Zenitude and Meander. We are checking in with the Port 2 Port Rally net on 8161 mhz at 0615 and 1815 EST. The Rally boats are going to Bundaberg but we will peel off and make landfall in Brisbane.
Today's highlight - discolored water as far as the eye can see. We are not sure what we are seeing. We are sailing northeast of New Caledonia, 120 miles away from the nearest land, in 4000 meters of water. Could the very small floating/suspended particles be coral bloom, discharge from a ship's tanks, evidence of an underwater volcano? If you have any ideas, let us know. We have no clue.
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