Night Diving

light

Unlike ( or just like ) the Caribbean, diving in New Jersey is actually better at night in many ways. That's obviously not true if you are out to survey a shipwreck, but for inlet diving, there is no comparison. During the day, the day critters will be wide awake, and you won't be able to get near them, while the night critters will be down in their holes where you'll never see them.

At night, you can go right up to the sleeping day critters and pinch them, even the fish. Some even seem mesmerized by your light, which will also draw in many small invertebrates by itself. Meanwhile, the night critters will be out prowling around, including the king of all night critters, the lobster. And if you shut off the light and wave your hands vigorously, the bioluminescents will put on a show for you.

Actually, if you go down deep enough at sea, the difference between day and night becomes less pronounced as the surface light is filtered out by the somewhat-less-than-perfectly-clear Atlantic water. Basically, any time that the sun is not shining brightly high overhead is going to be nighttime on the bottom. For this reason, you should always carry a light, day or night.


Nitrox

Human lungs are designed to extract the oxygen we need from air - a mixture of roughly 21% oxygen and 79% nitrogen, at a pressure of one atmosphere ( about 14.7 psia.) As you dive deeper and longer while breathing air, the increased pressure causes ever-greater amounts of both gases to dissolve in your blood and tissues. One would expect that eventually, such elevated concentrations would become troublesome, and indeed that is the case. As it turns out, nitrogen, with its greater concentration in the air, is the first gas to become a problem during a dive to recreational depths ( <130 ft. )

This problem is that of "off-gassing", or decreasing the concentration of dissolved nitrogen in the body at a rate that does not cause bubbles of the gas to form in the tissues and blood, the condition commonly known as the bends. One way to delay the onset of this problem is to decrease the concentration of nitrogen in the breathing gas, and the easiest way to do this is simply by increasing the concentration of oxygen. The resulting mixture is typically known as Enriched Air Nitrox and has become a staple in the diving community.