When we look at photos taken underwater, one of the first things we often notice is the clear, blue water in the background. If you’ve been a scuba diver for long, you know that great visibility isn’t always part of the package – and you know that low visibility is a fact of life at many sites. While clear water is always desirable, there are some times when diving in murky waters delivers exceptional rewards.
Low Visibility Diving: The Basics
Low visibility can occur because of darkness, silt, or plankton; it can be seasonal, or it can be something that’s always associated with a certain location. If you cannot see for more than a few feet, you can’t communicate with your partner effectively, it’s easy to become disoriented, and it is very easy to panic. Luckily, we modern divers have plenty of great tools at our disposal which simply were not available to the sport’s pioneers. Bright lights, reliable compasses, and dive computers are all indispensable tools for low visibility diving.
There are a number of reasons many choose to dive despite low visibility. Some actually enjoy the thrill of not knowing what they’re about to see. Others, usually public safety divers or commercial divers, don’t have a choice – they must simply do their jobs, no matter how well they can see. Scientific divers choose to visit low-visibility sites, as this is the best way to conduct research on the species or geologic features occurring there.
At some sites where clear water is present, low visibility might be caused by necessary diver activity. For example, archaeological sites are usually low visibility sites, simply because of the digging activity taking place. The same can be said of research sites, particularly when divers are burrowing in the sand or other substrate while collecting samples or searching for hidden animals.
At wreck sites, water outside may be clear while water inside the wreck is murky due to sediment; in addition, darkness is usually a fact of life for those who penetrate wrecks.
Equipment for Low-Visibility Diving
There are a number of items that make low-visibility diving a bit more tolerable as well as quite a bit safer:
-
Scuba Light Sticks: Usually available in red, green, and blue, these light sticks help divers to see and identify one another in the dark.
-
Dive Lights: Sometimes referred to as underwater torches, dive lights have powerful beams that penetrate dark water. In murky conditions, these lights may only be seen from a few feet away. It’s vital to carry a backup or redundant dive light in the event the first one fails.
-
Strobes or Marker Lights: Small marker lights or strobes can help divers to see one another, and they’re essential for boat diving at night.
-
High Visibility Lines: For cave diving, wreck diving, and many other situations, these lines make it much easier for divers to avoid disorientation.
-
Luminous Compass: It’s much easier to navigate in the dark or in murky water when one’s compass is easy to see. If you are not well-versed in navigation using a compass, be sure to work on that skill before heading to a dive site where low visibility is an issue.
Low Visibility Diving Techniques
One of the worst problems associated with low visibility diving is that it hampers divers’ ability to readily communicate with one another. In clear water, it’s possible to move a few meters away from your buddy with no issues since you can see hand signals with no difficulty. In waters with visibility at two to five meters, it’s necessary to stay closer together, often with the help of a buddy line. In even lower visibility, it’s best to use a reel and line to prevent complete disorientation.
Some additional tips include the following:
-
Good buoyancy control can prevent iffy visibility from becoming worse, particularly in areas where silt is prevalent or where very lightweight sand covers the bottom. In caves and wrecks, silt-outs caused by diver motions can be a serious problem.
-
When using a buddy line, use particular care to avoid entanglement and other hazards. Carry a sharp knife and a spare buddy line with you to ensure both you and your buddy stay safe.
-
When descending in low visibility waters, use extreme caution to prevent hitting your head on submerged items; when ascending, use care to avoid coming into contact with items on the surface.
Dangers Associated with Low Visibility Diving
Low visibility diving comes with some specific dangers. Awareness of these dangers can help prevent accidents:
-
When diving in low visibility conditions, take care not to bump into objects that can cause serious injuries: reef structures and sharp edges on wrecks are examples.
-
Some sites are plagued by current as well as by low visibility; in the event current is present, be doubly cautious to remain with your buddy, and consider using a buddy line even if you can see one another from a short distance.
-
Marine life can pose a serious hazard in low visibility; often, this is because these animals are on high alert due to an inability to see well. If you surprise an animal, it is likely to attack. Sharks, seals and sea lions, stingrays, and smaller animals are just a few creatures that might feel the need to defend themselves when startled.
-
When diving at low visibility, one tends to focus on seeing what is happening in the environment. Although it is vital to remain aware of your surroundings, it’s also important to keep a sharp eye on your gauges to ensure your air supply is adequate and to be sure that you are following the appropriate dive profile.
-
Panic can happen to anyone, particularly if nitrogen narcosis begins to set in during a low-visibility situation. Pay close attention to the way you feel while diving at low visibility, and remind yourself of the many safety measures you’ve put in place to prevent problems. If you feel yourself panicking, alert your buddy and consider aborting the dive. While returning to the surface, be sure to make a controlled ascent and do not skip safety stops.
While low-visibility diving is dangerous, it can also be fun, so long as you are knowledgeable and capable of using the necessary safety equipment. Dive site knowledge, a suitable buddy, and good planning will help you to get the most from your dive while staying safe.