I am a warm water diver and where I am currently in Upstate New York, there is no warm water diving. However, one of the local dive shops has gotten me interested in an upcoming dive. It is a river dive that connects two nearby lakes. They claim the water is getting warm (weather service says it is 16.1°C / 61°F today). It is a drift dive, with an estimated current of 4.3 knots, that is 5 miles per hour or 8 kilometers per hour. The dive is shallow about 15 to 25 feet/ 5 to 8 meters and visibility is expected to be between 30 to 40 feet/ 9 to 12 meters. The RU4Scuba sign up page gives the dive time as about 45 minutes, depending on the current. This will end the dive well before the point where the name of the river changes from Upper to Lower and the current can reach 60 miles per hour/ 100 kilometers per hour. The two lakes are Lake Erie and Lake Ontario. The river is the Niagara River and the point of the name change is called Niagara Falls. Yes, I really do not want to be close to that in the water.
The Niagara River carries waters for Lake Erie, one of the Great Lakes, into Lake Ontario. Two hundred miles away (320 kilometers) Lake Ontario empties into the Saint Lawrence River/seaway continuing on to the Atlantic Ocean. Here there are also currents but often not as strong as the Niagara. Some dive sites have less than a knot where a strong current could be up to 4 knots. The St. Lawrence is not as well known as a drift dive destination as it is a wreck destination. The Great Lakes may be lakes, but they have some of the worst sea conditions in the world, and the number of missing ships proves it. The water here is fresh water, cold most of the year and has a low oxygen content. Shipwrecks centuries-old look like they been sunk only weeks. The St. Lawrence is wide and with a low current in places, many of the dive sites start and stop at the same point. Other locations, they are done as a drift dive.
While in some rivers, the current may be mild enough that you use the same entry and exit points, it is common to do river dives as a drift dive. On any drift diver, there are extra precautions that need to be taken, on river dives, there are other items to be concerned with as well.
River Drift Dives
Just like every ocean dive site is different so is each river dive site. However, a section of a river can change dramatically with no notice. A heavy rain that you did not see, might change the speed of the current. A dam opening upstream might do the same. Search online for the keyword flash floods and look at some of the videos. Rivers can change in minutes. Proper planning is a must with river dives.
Unless you are diving in a river feed by an alpine lake with crystal clear waters, visibility is likely to be poor. Runoff from fields, algae in the water, silt and the turbulence in the water can reduce visibility to zero. A good separation plan appropriate for the river must be established between the divers. Some dive teams will tether themselves together or both have a tether to a surface float. The reduced visibility and the speed of the current may cause you to run into things underwater. A branch that has been wedged under a rock, or even a large rock. Recreational divers have even come across missing cars. The depth of a river will almost always be uneven.
While there are a few hot spring-fed rivers, most river diving is colder that diving in a still body of water. Moving water will not heat as rapidly as still water.
Do you need any additional equipment, maybe a question in your mind? Again it will depend on where and how you are diving. Mostly you will not need anything additional that you would not be using on any drift dive and low visibility dive. You might hear a reference to a river tool. That means different things to different divers. Primarily it is a tool that is used to hold you in place on the river bottom. Similar in function to a reef hook, holding you in place on a wall drift dive. One device commonly used is a handheld gardening cultivating hoe. These tools have three tines that are used to break up the soil to plant the seeds. A diver can use them to hook into the bottom. They can also be used as a digging tool if the needs arise. A cutting tool is important as well. One friend of mine has a smartphone in a waterproof case in his dive float. At the Beginning of the dive, he starts his GPS and a hiking app. When the dive is done he has an accurate representation of the path of his dive as well as the speed which he traveled.
River Clean Up and Treasure Hunts
There are two other things that seem to come up when talking about river diving. River cleanups and treasure hunts. These are similar activities, just the motivation is different. Many environmental organizations and dive centers will plan river cleanups. Generally, they will have volunteers working the banks of the rivers with divers cleaning debris from the rivers themselves. These are often held on Earth Day or Coastal Cleanup day, but anytime you can do one would be great.
Divers who do treasure hunts often dive where a large number of people are involved in activities such as boating, tubing, and kayaking or near bridges and piers. Places were someone not paying attention might drop something in the water. Cell phones, wallets, and jewelry are often found. People sometimes forget what they have in their pockets until it slips out and falls into the river. Divers who are dedicated to treasure hunts will often purchase specialized equipment such as underwater metal detectors.
Why River Dive
Why river dive? Because it is there. A local river may give you the opportunity to dive more frequently. Because of the changing nature of a river, you can dive the same location a number of times and have a different experience. Many river dives are done from the shore. You do your dive plan, select where you will finish. Determine the approximate current, factor in your projected dive time and determine where to start. Leave a car at the finish and drive to your starting point and drift back. The options will be determined by your dive conditions and the rivers, but it opens up many possibilities for many divers who are limited otherwise.