At https://earthobservatory.nasa.gov/images/37061/the-bahamas/ … from NASA Eareth Observatory – east of Florida large swathes of the ocean glow peacock blue. They are this irridesence due to their shallow depths. The under water terrain is hilly and the crests of some of those hills comprise the islands of the Bahamas. In 2009 clear skies allowed NASAs Aqua satellite to take the picture below …
the sharp oultine of the banks indicate the ocean floors drops dramatically around them. Over the banks the water depth is often less than 10m – just 33 feet deep. The surrounding basin plunges to depths as low as 4000m – some 13,100 feet.