By Jeanne Bear Sleeper
Night diving expands scuba into a 24 hour sport! Once you have seen a reef in daylight, a moonlight view is amazingly different.
The night reef displays its critters who were hidden in holes during the day or who transformed themselves at twilight. The critters' different night behaviors make you wonder if they are the same fish you saw while day diving.
Animals "get in your face" at night. Instead of swimming away, they are attracted to your light or the mirror reflections on your face mask glass. They march right up and check you out at close range. Other animals are mesmerized by the light and stop in their tracks. You can approach quite close as long as the light remains focused on the animal. When you move the light, they swim away looking somewhat confused.
At night some parrotfish spin a mucous cocoon around their entire body. This shimmering fish looks like it is in an oblong acrylic display case tucked into the reef. You can pick up the cocoon and take great photographs, just remember to gently return it to a safe spot. Animals in different areas exhibit other unusual behaviors. Experienced divemasters can tell you what to look for on a particular dive.
While you are mesmerizing fish, try not to blind your dive buddy. If you shine your dive light into your buddy's face, all he or she can see for a few seconds is sparkly dots. Work hard to keep your dive light pointed at the reef. If you need to get a buddy's attention, wave the light beam back and forth across his/her line of sight or worst case, across the lower part of his or her body.
Resort and Boat Night Diving is Easy: If you have never been night diving, doing it with an experienced group makes it much easier. Most resorts and live-aboard boats schedule night dives. Plan ahead at the beginning of your trip so you dive the same reef in daylight that you will dive at night.
Resort and boat divemasters know the reefs, are accustomed to handling tourists with nervous jitters and know the marine life. The divemaster can give a very thorough briefing about the reef, which takes away much of the fear of the unknown.
Most resort night dives are from small boats. This really makes it easy-no long surface swims and you have an anchorline for descent and ascent. If you go down an anchorline feet first, clearing your ears will be easier. By shining your light around the whole area, it will help set aside any fears you may have that something big and nasty is going to swim out of the dark.
Tropical water is usually very clear and you will be diving on a shallow reef so, with a good light (especially if there is a full moon), you'll be amazed at how much and how far you can see.
Most resort night dives begin at twilight, so you can reasonably have dinner after the dive. Not having a full stomach is a good idea on your first night dive. If you have a tendency to get seasick or disoriented, an empty stomach is better.
Some divers worry about getting separated from the group. If you have a regular buddy, remind him/her you want to stay closer together than normal. If you are paired with another resort diver, insist he stay no more than an arm's length away. If he doesn't agree, ask the divemaster for a different buddy. Once underwater you will be surprised how easy it is to see each other with the dive lights and the chemical lightsticks that most resorts supply. The lightsticks, which are tied to the scuba tank, come in several different colors and are good for one dive. They throw off an amazing amount of light and make it very easy for the dive boat staff to track your progress through the water.
Some resorts offer larger boats and have the space and equipment to hang generator powered high intensity lights in the water. It's fun to try, because you can shut off your personal light and dive in the glow of the big overhead lights.
One caution: The big light clusters attract marine life like bugs to a porch light. It's wild to see Flying Fish rocket to the surface or squid move like a giant bait ball. As a beginning night diver, I always wondered what big set of teeth looked at the squid (and me) like an all you can eat buffet!
Dive Lights: To have a safe and enjoyable night dive, you will need some additional equipment and extra planning.The most obvious equipment is a dive light.
These can range from flashlights for under $30 to larger lights with six volt or multiple battery power sources. The larger lights have a handle (other than the light's barrel) and are powered by dry cell or rechargeable batteries. This style light ranges from $20 to $100, depending upon the case material, power source and type of bulb assembly.
There is no one right light. It all depends on the amount, location and activities planned for your night dives. You may even want to choose a secondary light that is small enough to take on day dives for hole peeking and color enhancement, plus use a larger model as your primary light.
The one light or two light debate could go on for pages but my opinion is that common sense ought to prevail. If several buddy pairs are diving in clear, warm water, a la Caribbean resort style, then one average light per diver is common practice. On the other hand, if two divers are night/wreck/game diving off the beach, then each diver will want to carry two of the heaviest duty, most reliable lights they can buy and also consider wearing an arm strobe for emergency signaling. The conventional wisdom from the training agencies is take two light sources whenever there is limited visibility.
Features to consider when selecting a dive light:
1. Beam width
2. Weight in air. If you face a long hike to the dive site, you might want to consider a lightweight light.
3. Buoyancy. A light that floats could be an advantage or disadvantage depending upon where you dive.
4. The on/off switch. Can the light be turned on and off easily with one, gloved hand? Too easily? Will the switch get turned on accidentally?
6. The availability of a wrist lanyard
7. Beam strength. Does the light seem bright enough for the color and clarity of water where you usually dive?
8. Depth limit
9. Warranty period?
10. The frequency of your night diving excursions. Dry cell batteries are less expensive, but only if you use the light infrequently.
11. The O-ring seal. Does it stay in place when opening the light or will it be easy to lose or crimp (and flood) when changing batteries?
12. If most of your night dives are made while traveling, which will be easier, more available and cheaper-disposable or rechargeable batteries?
13. Does your local dive store stock the common replacement parts?
14. What lights do your buddies use- would they repurchase the same light?
Techniques and Practices: Buoyancy control is the number one skill to concentrate on while night diving. Improper buoyancy control results in reef damage. If you are kicking wildly, the chances are you are going to break plants and smash animals. So it is critical not to be overweighted. Ideally, a diver would hover slightly above a reef, never coming in contact with anything alive. If you want to stop and kneel down to watch the life, do it on a bare patch of sand.
Buoyancy control is a little harder at night, because your depth perception may be off a little and your hands are busy with a light. If you are not used to carrying anything while diving, the manipulation of a light can be enough to make your movements awkward. If you have a chance to carry a light during a day dive, it is good preparatory training.
Being positively buoyant is a problem as well. If you keep floating to the surface, your buddy is going to have a hard time staying in close contact. Test your buoyancy during the day dives, so you are confident you have the right amount of weight for the thermal protection and type of tank you plan to use at night.
Some people add one or two pounds to their weightbelts the first few times they night dive. You may consumed air faster on your first few night dives, because you over-breathe when anxious or worried. The extra weight helps offset the buoyant effect of taking bigger breaths. When you calm down after a few night dives, return to your normal weight. Don't add more than one to two pounds or you will need to add excessive air to your BC.
Even if your buoyancy control is excellent, you will probably brush into something during a night dive. To avoid skin irritation and cuts, wear some type of protective suit. In the warmest waters this may be a Lycra skin. In cooler tropical waters it might be a 3mm suit. If you only have a lightweight shortie, then consider wearing heavy tights and a long sleeved T-shirt.
Once the sun goes down even the warmest tropical climates cool off. You will be more comfortable if you wear a thicker suit night diving than you wore during the day. Also, bring a jacket and warm clothes for the ride back to shore.
Summary: Night diving is a wonderful underwater experience. Consider plunging into a world where a wave of the hand produces a phosphorescent trail of twinkling light, where the critters come to see you and where you can experience many organisms feeding and looking totally different than they do during the day.
There is also an inner experience that comes with night diving. Your senses come alive and you hear new sounds, such as shrimp clicking and reef fish grunting. You also confront your personal fears about the unknown and gain a new confidence from a successful night dive. Try it on your next tropical vacation for a spectacular underwater experience!