I certainly agree that you should keep an eye on your computer closely, especially on ascent, and especially to monitor your ascent rate. But don't dismiss your instructors advice about color and light. I also have a very easy time clearing. I wouldn't call it effortless, but after a day or two of consecutive diving, I don't usually have to consciously clear my ears. Over years of focusing on photography, I have a pretty good sense of my depth based on the loss of color. You can find charts, like this one:
(Basic Principles of Light Underwater)
that detail what colors of light are lost at approximately what depths. Of course this is different for predominantly green or blue water, and depends on the overall visibility and light penetration. But you can develop a pretty accurate sense of how deep you are by observing how much color is left, or how completely blue/green your visual field is.
(Basic Principles of Light Underwater)
that detail what colors of light are lost at approximately what depths. Of course this is different for predominantly green or blue water, and depends on the overall visibility and light penetration. But you can develop a pretty accurate sense of how deep you are by observing how much color is left, or how completely blue/green your visual field is.
