No Diving in Waitemata Harbour?

I live in Birkdale, Beach Haven wharf is the closest sea water from our place. We often walk there to relax, enjoy the sunset, have a glass of wine. When I see the coffee-like water I know no (reasonable) diving is possible. However, sometimes at high tide with no wind from the west the water gets reasonably clear (perhaps more than 2m visibility?) … and I dream about rocks on the bottom of the harbour covered with huge sponges and attracting marine life. The water flow is strong, it brings a lot of nutrients it should be possible to find such a dream spot. However, would it be possible to actually SEE it? Wasn’t it buried under layers of mud long time ago? I keep dreaming.

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