Both good images Drawbridgep. Sunlight penetrates up to 100 feet or some 30 meters before then certain colors are filtered out of the light at different depths. And sharks have been known to go as deep as 700m. Deep north Atlantic turbid waters have that eerie greenish appearance whereas warm tropical waters are clearer and exhibit that bluish ting which is the last color to be filtered out of the water. Id go with that greenish image because it invokes that creepy feeling of not knowing whats beyond the murkiness. I also agree that in waters at these apparent depths, caustic patterns in any great intensity would not be visible.