Diving in freshwater environments is much like diving in marine environments in many ways. While freshwater dive sites are intriguing, and, while the aquatic life you’ll encounter is interesting and sometimes very surprising, the hazards you may encounter when diving in lake environments are somewhat different than those commonly encountered in seas and oceans. Once you’re aware of the hazards different sites pose, though, overcoming them can be simple. Let’s take a closer look.
High Elevation
Many of the world’s most spectacular lakes are situated high above sea level, and to get to them, you may find that you’ve got to hike, climb, or drive some distance. One of the most important rules to remember with lake diving at high elevations is that depths and durations will vary depending on altitude. In case you’re wondering, any dive site higher than 300 meters above sea level is considered a high altitude site; keeping your dive computer on at all times before and after altitude dives can help prevent DCS. At high altitudes, atmospheric pressure is different than it is at sea level. Make descents and ascents carefully, and wait at least 12 hours between arrival at altitude and your first dive; pay close attention to the rules of altitude diving and make no exceptions. Careful planning is the key to accident prevention in this case.
Remote Locations
Diving in remote locations is usually incredibly rewarding; yet, it is not without hazards. The same seemingly minor accident that takes place in an area where help can arrive quickly can become a major incident in a place where assistance is far away; the hours it can sometimes take to get to a hyperbaric chamber can be excruciating and even deadly, and the costs associated with getting emergency help to a remote area can be astronomical. Enjoy these dives, by all means; but be sure to assess risks and make your plans accordingly.
Boat Traffic
While some lakes have specific areas set aside for divers, far away from boat traffic, the majority of lakes simply advise divers and boaters to be aware of one another. Depending on where you dive, you could be up against boaters who are under the influence of alcohol, or you might find yourself in an area where boats and jet skis speed along without regard for dive flags. Every year, divers are injured and killed in accidents with boats. Avoid becoming a statistic by paying close attention to your surroundings. Listen carefully before surfacing, and never, ever dive without a flag – whether you think boaters will notice it, or not.
Entanglement and Snags
Some lakes are beautifully pristine, but in many places, particularly in man-made reservoirs, snags and entanglement hazards are numerous – particularly in areas where fish like to spend their time. In places where fishing is allowed, you not only need to be careful of the fishermen and their boats, you need to watch out for lost fishing line – it is almost impossible to see in many cases. Carry a sharp dive knife and a redundant knife, and keep a mesh bag with you so you can clear up any hazards you encounter. Besides fishing line, look out for snags, such as old sunken trees and construction debris around bridges and dams. Be aware of your surroundings at all times, move slowly, and if you are stuck, do not panic. Remember your training, and if your equipment is damaged, abort your dive as soon as possible.
Dam Intakes and Other Mechanical Devices
Underwater structures are fascinating, and dams can be excellent places to find aquatic life. When diving around dams, pumping stations, and in other areas where mechanical means move massive quantities of water, keep your distance from suction devices. Don’t be tempted to go closer for a good look at machinery; in this case, any mistake you make might be your last. Suction hazards tend to be greater when water levels are low, and suction can happen quickly.
Cold
Lake water can be warm in the shallows and near the surface, and ice cold just a few meters beneath the surface. This phenomenon varies from one lake to another; in any case, learn what you can about water temperatures before you dive; and always wear thermal protection since exposure to bone-chilling cold can cause increased air consumption and increase your risk of hypothermia. If you find yourself becoming chilled, finish your dive early; another side effect of cold exposure is that it prevents you from thinking clearly and decreases concentration. By the time confusion sets in, it can be too late to egress.
Reduced Visibility
If your dives have mostly taken place in clear ocean environments where you can see for tens of meters, be prepared for greatly reduced visibility when diving in lake environments. In most lakes, particularly in areas where the water is warm, microorganisms living in the water cause reduced visibility and silt collects on the lake bottom, just waiting for a misplaced kick to stir it up. One of the best ways to ensure you’re benefitting from the best visibility possible is to dive on days when activity is at a minimum. Another way to make sure you can see as far as possible is to pay close attention to trim and buoyancy – watch every motion carefully. Buddy awareness is extremely important here – in some cases, you might not be able to find each other if you are separated. Make a dive plan and stick to it; plus, be prepared for contingencies. In addition, remember that reduced visibility increases the hazards associated with the other risks we have discussed.
Don’t be fooled into complacency when diving in lakes. Despite their often small size, their calm appearance, and their scenic beauty, they can be very dangerous places. Carry redundant equipment, watch your depth, and stay in contact with your buddy at all times; and, don’t forget to tell someone what your plans are. Register onshore if required, and follow any posted regulations. By taking these precautions and using proper technique, you can enjoy some truly wonderful dives – all without the need to rinse salt from your gear when you’re finished.