Blue holes are thought to be sink holes. These can occur on the floor of the ocean or even on islands. Over eons, new reefs or caves are created over the sink hole. Still evident are venting bubbles gurgling up gasses.
National Geographic has done several episodes on Blue holes. Because of their “undisturbed” nature, they can be a look-back in time for geologic events, prior inhabiting species and serve as a window for available plant species and food sources of creatures inhabiting the seas and islands in the Bahamas.
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