Standing on the edge of Manly wharf looking down over 4 metres and it's crystal clear with fantastic visibility. You would think you were in Noumea. Nice sandy bottom too apart from 5 bicycles down there.

I guess all those congested home units up the Parramatta river do have one upside as they're all on X industrial sites.

Moreton Bay clears up in winter as well, has it got to do with water temperature?

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cammd said..
Moreton Bay clears up in winter as well, has it got to do with water temperature?

Was certainly beautiful at Tangalooma 6 weeks or so ago but I don't think the water temperature had started to drop yet.

I was on the boat at Pittwater yesterday and would normally expect Pittwater to be a bit clearer than the harbour but if anything it's the reverse at the moment.

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cammd said..
Moreton Bay clears up in winter as well, has it got to do with water temperature?

Possibly, but the other big factor for us is lack of rainfall lately. No stormwater run off makes a huge difference.

Snorkeling at Lord Howe is much clearer in cooler water temps than it is when warmer. I'm told it is very much temperature related.

less 'stuff' in water in winter / cooler water....which is why hull growth slows down during colder weather, Vs you can almost watch the hard shell grow in Summer (Jan Feb March) water temps

But what doesn't make sense is why tropical waters are so crystal clear. The typical turquoise waters that you see in the tropics (far away from mainland runoff) is due to the absence of phytoplankton in the water.

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Phoney said..
But what doesn't make sense is why tropical waters are so crystal clear. The typical turquoise waters that you see in the tropics (far away from mainland runoff) is due to the absence of phytoplankton in the water.

I've snorkeled in Hawaii, Bora Bora, New Caledonia and the water was always murky. Tahiti was the worse though. I did not go in the water it was like soup!

Depending on the time of year, tropical waters can get soup like when corals spawn so that maybe that was it? When I sailed around Tahiti / Moorea it was pretty clear and turquoise

Anyway this page explains ocean colours

science.nasa.gov/earth-science/oceanography/living-ocean/ocean-color#:~:text=The%20bright%20white%20calcium%20carbonate,the%20water%20deepens%20to%20azure.

In coastal/littoral waters the Salinity can have amassive impact on turbidity.
The more ionized (saltier) the water, the clearer it is.

In areas where a river/creek outflow enters a salty body water can have a really crisp delineation between fresh and salt water. With sediments etc dropping rapidly out solution as the two waters mix.

As mentioned above, this is not the only factor