Dusk Diving

By Bill Gleason


What better way is there to usher in the New Year than with a brand new, exciting type of U/W experience? Called dusk diving and snorkeling, it takes place as the sun sets. The hour just before sunset is the most exciting time on a coral reef but divers and snorkelers are often sipping cocktails instead of enjoying the show. Consider these simple facts:

1. During the long hours of the day, the reef is dominated by the species of fish that feed during these hours (parrotfish, angelfish and damselfish just to name a few). They feed in established territories on the reef, traveling to them every morning. As the sun sets, their internal clocks tell these fish it's time to go home and they begin the journey back to their night resting places. This migratory behavior is different than daytime grazing behavior and can only be seen at dawn and dusk. This change in behavior does not go unnoticed by other fish.

2. There are many carnivorous fish on the reefs during the day whose coloration was superbly designed by nature to be particularly effective in low light conditions. Guess when they make most of their feeding moves? You got it, at dusk. This behavior is easy, fascinating and safe to watch.

3. Scientists roughly estimate that about 80 percent of all fish mate at dusk. Their mating/spawning rituals are completely different than their other daytime behaviors. You can glimpse this on almost every dusk dive, particularly during the summer. While rituals differ with each species, there is usually a competitive courtship that may involve a single female and several males. Once the female has selected her mate, the couple perform a dance that finds them spiraling through the water toward the surface. Near the surface, they perform a graceful arc and the female discharges her eggs, which are then fertilized by the male. The ritual concludes with a graceful descent to the relative safety of the coral reef. It is very rare to see this dance during the day but very common to see it at dusk.

As fascinating as diving during the day is, it pales with the excitement of dusk diving. This activity needs no special equipment or special training. Both snorkelers and divers can do it anywhere there's a coral reef. There are a couple of obstacles, however. First of all, nearly all dive boats are securely tied up at their moorings when the sun sets, making it difficult to get to a dive site. Also, all of the divemasters are either filling tanks or have gone home, so there's no one to lead the dive.

These are not insurmountable problems but it does mean we will probably have to ask specifically for the opportunity to try a dusk dive. There are a couple of pioneering resorts that are opening up their schedules to accommodate dusk divers but the majority of this type of diving is now done without benefit of either boats or divemasters. This can and will change rapidly as folks discover the fascination of dusk diving and snorkeling.

Strangely enough, in the current state of tropical diving affairs, many divers may find themselves en route to a site during sunset hours. It's very common for resorts to load the boat for a night dive just before sunset and cruise to the site as the sun sets. While convenient for resorts and divers alike from a scheduling point of view, this short changes the diving experience. The last hour of sunlight is a hot time on the reef, not the first hour of darkness. And, it takes about an hour for the reef to completely change from the day shift to the night shift. The hour right after the sun sets is a transitional one and not the best time to view the splendors of the night reef.

Consider dusk diving on your next dive vacation and let your favorite divemaster know you'd like to give it a try! And, from the entire staff at SDM, our best wishes for a prosperous New Year!