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DAN – Diving at Night

Diving at sunset
Diving at sunset

The ocean is a mystifying place, and when the sun goes down, the allure only intensifies. At night, the ocean more closely resembles outer space than Earth, so it is no surprise that adventurous divers list night dives as some of their most thrilling experiences. Think you have what it takes to dive in the dark? Follow these tips to make sure your next night dive is flawless.

By Caitlyn Ruskell, DAN Content Writer/Editor

Start by planning your night dive at a site you have dived during the day: You will be amazed to see how places you have been to hundreds of times can suddenly become uncharted territory as new, strange organisms come out to play. Arrive at your dive site around sunset and do a survey skin dive to assess conditions and get a good look at your site as the lighting changes. This sunset snorkel will help you maximize your bottom time on the night dive and will give you the opportunity to see some crepuscular organisms, which are most active at dawn and dusk (sharks, for example).

Double manta
Double manta

Once you deem conditions good enough for diving, get ready to gear up. Just like on any other specialized dive, you will need to bring specific equipment along for a night dive. Arguably the most necessary piece of equipment for your night dive, aside from your scuba unit, is a good set of dive lights: Make sure you have both a primary and a back-up light.

When you dive at night you can only see what you illuminate with your dive light, so normal hand signals may not work. Review proper night signals with your buddy before you hit the water to make sure you are both on the same page. Additionally, mark the things you want to recognize with strobes such as an exit ladder, an anchor or an ascent line. For easier recognition of your dive buddy and divemaster, mark everyone’s cylinder with colored glow lights. Each pair of buddies can have their own identifying color. This way you will not have to risk shining your light in someone’s eyes to get a look at their face (this is rude, by the way, and you should avoid it). Keep your primary light on throughout the dive. If you want to experience a “lights out” effect, press your light against your body instead. In places with bioluminescent organisms, dimming the lights makes it easier to see them fill the surrounding water with colorful, glittering light.

When you begin your journey away from your starting point, pay special attention to your compass. Natural aids to navigation become extremely and sometimes impossibly ineffective at night, so compass navigation is the way to go. Again, since you only see what you shine your light on, it makes discerning compass error due to currents or human error very difficult. Try using a simple method of compass navigation, like following a reciprocal course, for your first night dives.

Likewise, spatial awareness is more challenging at night, so pay close attention to your buoyancy using a depth gauge or by hovering close enough to the bottom to see it. Stick right by your buddy’s side: Getting separated at night is even more dangerous than it is during the day and it is much trickier to troubleshoot.

Throughout your dive, be wary of overexertion or getting cold. Remember that water tends to cool down at night, so it may be necessary to wear more thermal protection than you would during the day. Plan your dives around the cooler temperatures by ascending even slower and diving a more conservative profile; it may help you avoid decompression sickness (DCS). When you exit the water, dry off quickly and bundle up in a sweatshirt: Hypothermia is a real concern, even in tropical destinations. Following these tips will not guarantee a perfect night dive, but they will help you make the most of an adventure into the dark. For more dive safety information, visit DAN.org.