So if you've never snorkeled at night, you're missing half the fish, a plethora of nocturnal invertebrates, and at least half the fun. We will treat night snorkeling in a separate article, but it's in the fading illumination of dusk that we as snorkelers can view the reef in an entirely new light. In many ways the reef can be compared to an urban zone. Not just a town, or even a substantial city, the reef is more like a major metropolitan center bustling with activity, day and night. During this time behaviors alter radically.
Predation is at it's peak.
As snorkelers, this is one of the very most exciting times to observe the reef community. Visual ability is a fundamental survival skill among creatures of the reef, especially fish. This is no easy task considering the highly competitive nature of reef life. By necessity, the eyes of fish are remarkably sophisticated. Many fish are also capable of binocular vision, allowing a keen sense of depth perception necessary for navigating the complex, three-dimensional coral world.