Night diving – both glorious and nerve-wracking – DIVE Magazine

The last light of day disappears just a few metres below the water’s surface (Photo: Didier Barriere Doleac/Shutterstock)

Night diving can by turns be exhilarating, luminous, beautiful – and panic-inducing. Former dive instructor Mark ‘Crowley’ Russell explains why

Nobody forgets their first night dive. It’s a strange and otherworldly experience, where the ocean comes alive with life forms that you often either don’t see at all during daylight, or which exhibit behaviours so drastically different from their daylight activities that they appear to be divergent species.

Octopuses, often camouflaged and hiding from sight during the day, are active hunters at night. Slow-moving lionfish, a tropical diver’s favourite, do very little of anything during daylight hours, but turn into voracious, fast-moving predators under cover of darkness.

Reef-building corals, as stony as their description while the sun shines, bloom like gardens of ravening flowers at night, the polyps insistently extending their tentacles to grasp at passing sources of nourishment. The largest migration of all animal life happens after sunset, as billions of tiny creatures head towards the surface to feast, before returning to the depths with the rising of the sun.

It’s not just the ocean life that is different, however – divers themselves often exhibit unusual behaviours at night, not only because of what they might see, but also what they can’t see, and don’t see – such as you, the dive buddy they just kicked in the face.

Octopuses are far less shy while hunting in the darkness (Photo: Julian Gunther/Shutterstock)

Diving in the dark is entirely analogous to surface-based activities, such as walking through city streets late at night, a very different experience with a very different atmosphere to that of the day. Or the park where you spend your lunchtime enjoying the sunshine that now feels like a dark and dangerous place; the trees that earlier provided shade now looming out of the gloom and shadow…

It was close to Hallowe’en at the time this article was written, hence the metaphor tends towards the baleful, but also lends itself well to the first law of night-diving: always dive a site with which you have more than just a passing familiarity, so at least you have some idea of what to do, or where to go, if something goes wrong and you find yourself disoriented underwater.

First, consider the conditions: I doubt that even the most experienced divers would dive at night in deep water with big currents and low visibility. While night diving is immensely beautiful, it is an additional stressor and small problems can be greatly exacerbated by the dark. A large swell can prevent you from being seen at the surface, so, clear, calm and shallow, is the order of the day, as it were.

It is often worth beginning a night dive while there is still some light in the sky. Assembling and checking your gear will be easier, as will getting into the water, especially if you are shore-diving and have to negotiate a tricky entrance over rocks or through surf.

Even if you begin your descent just after sunset while there is still some light in the sky, the reduced visibility and the physics of light penetration mean it will be virtually pitch-black once you’re a few metres underwater. Before you descend, take a good, long, look at all available light sources. If you are boat-diving then the boat should be using night lights, which will serve as your point of reference.

Lionfish, almost sedentary during the day, are voracious predators by night (Photo: Kjeld Friis/Shutterstock)

If there are multiple boats at a dive site, note their relative positions. The boats may move, of course, but keep the light sources in visual range if possible – it’s better to exit onto a boat that is not your own rather than not end up on any boat at all.

When you’re diving from shore, take a reference from what is available – be that the light from a nearby building, or the moon, if it’s visible – and orient yourself to the shore while noting its position. If nothing else, should you become disoriented underwater, you can surface and the light will guide you back to shore.

High-intensity strobes are readily available and inexpensive, and are great for marking shot lines or exit points where there is little available light; it’s always worth having multiple sources of light for additional security. Try to keep reference lights visible as you descend, and, if possible, re-locate them from time to time during the dive – it’s rather reassuring to know that you have a connection to your exit point, and the surface.

It goes without saying that you will be diving with at least one torch, and preferably a backup. The days of the old, warm and soothing glow of the randomly exploding filament bulb are thankfully long gone, but make sure your batteries are charged, and you should still turn your light on (and keep it on) before you get into the water.

While backup lights are not always mandatory, consider the size of the dive group. It’s unlikely that every torch in a group of eight divers is going to fail, but in a group of two, the odds are much shorter. Ideally, every diver will have two lights, but if this is not possible, use good judgment with respect to location, group size and water conditions. If you’re guiding – and especially if you’re a professional diver – then a backup is essential.

Starting a night dive while daylight remains assists with tricky shore entries (Photo: Shutterstock)

As with all diving, buddy separation should be kept to a minimum, but underwater, dive lights can make it easier to locate your dive team at night should you find yourself away from the group. It’s also useful to have individual buddy markers, especially if you’re diving as multiple teams. Some divers use the aforementioned marker strobes attached around their tank valves, but – personally – I find these rather annoying in close proximity. A better solution is coloured Glowsticks; either the chemical variety as favoured by Nineties clubbers, or the more environmentally-friendly LED versions.

Signals inevitably change underwater. There are official versions as taught during club or agency-sanctioned courses, but at the very (very) least, have a pre-dive recap to make sure each member of the team knows how to draw their buddies’ attention, communicate their air-supply level, and signal ‘Okay’ and ‘problem’. Make sure you can identify your buddies by their gear, so that you don’t compromise another diver’s night vision by waving the light in their face when you’re signalling.

As mentioned earlier, night diving is an additional stress factor, and does tend to engender some extra nerves, even among relatively experienced divers. Together with the different visibility characteristics, dive teams often find themselves bunching up together more tightly, meaning extra unwanted contact and fins-in-the-face. It is also often the case that individual divers burn through their air more quickly, so limiting your depth and making air checks more regularly than usual is warranted.

Divers should always endeavour to plan their dives and dive their plan, and this is especially true at night. The darkness lends an unfamiliar aspect to even familiar surroundings, and distance perception is altered. Take note of as many visual references as possible when you’re navigating, and pay attention to depth changes, sand ripples, outstanding rock formations or coral blocks, factoring them in together with your reference light sources when possible.