LAFlyer, the visibility problem occurs elsewhere on the Big Island. From what I was told, there are quite a few underground streams, some of which come out in the ocean, and, as you noticed, the mixing of fresh and salt water clouds the visibility quite a bit. However, I don't know if that's the main cause at the Orchid. I suspect there must be also a certain amount of runoff from the watering of the grounds. If you swim out a bit farther, the visibility improves quite a bit.