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How a Stationary Vehicle Can Kill You

Craig Nelson

Is a parked car dangerous? Do you think twice before getting in or out of your own car, opening its trunk, or even just walking around it? Of course not; we do those things every day. What happens, though, if we put the same car underwater? Do you think of how you will move around the submerged vehicle, about how you will open its trunk, or how you will reach inside it? All public safety divers should; but, unfortunately, many do not.

Public safety divers are often called upon to respond to a vehicle in the water. The problem is that many public safety divers simply have not been taught the hazards of working around submerged vehicles. Admirably, they are focused on making a rescue, recovering a body, or searching for evidence; however, that focus too often becomes tunnel vision when divers fail to consider fully how dangerous working around a vehicle underwater can be.

Perhaps familiarity is part of the problem. Every day, we are close to, or even inside, stationary vehicles. They certainly seem harmless as we climb in and out of them, walk around them, or open and close the trunk. In an underwater environment, though, that vehicle we are so familiar and comfortable with becomes a potentially deadly obstacle course. Divers have died or been severely injured while working on a vehicle underwater simply because they were not trained or did not appreciate the potential dangers such vehicles present. What are those hazards, as identified and analyzed by Butch Hendrick for the Lifeguard Systems’ Underwater Vehicle Extrication Course?

Overhead Environment and Entrapment

On land, we climb in and out of cars several times a day, so we tend to think nothing of entering a car underwater. But, when was the last time you got in your car with a full exposure suit and scuba gear? That roomy sedan suddenly seems a lot smaller when you are wearing bulky dive gear. When divers poke their heads, arms, or even whole bodies into a car, they have entered the most dangerous diving environment possible: an overhead restriction that prevents direct access to the surface. Any overhead environment, whether car, ice, cave, or floating dock, is extremely dangerous and requires both training and careful procedures. Because they are such a small space, cars and vans can be particularly dangerous, because they do not allow a back-up diver to reach a trapped primary diver easily to provide air and assistance getting free. Also, because submerged vehicles may have been damaged before or during water entry, the space within may be even more restricted. Remember that loose carpeting and upholstery inside a vehicle, or a body released from a seat belt, can trap a diver as well.

To reduce the risk of being caught inside a car, divers must always carry bungee cords and use them to secure doors, trunks, and tailgates open before reaching into the spaces beyond. Otherwise, they may simply be setting a large bear trap for themselves.

When was the last time you climbed in and out of an upside-down car? A study by the Michigan State Police, Project Submerged Transportation Accident Research (STAR), found that if a vehicle enters water over 14 feet deep, it will nearly always turn over on its roof, so divers are likely to find that a submerged vehicle will be lying on its roof. Entering an overturned vehicle can be extremely disorienting, especially if the car is in low- or no-visibility water. Hence, it becomes extremely important that divers learn to work in an upside-down position, to move slowly and cautiously, and to use their mind’s eye to help them explore the interior of a submerged vehicle and remove victims or objects.


As if public safety diving did not already offer enough opportunities to become entangled, submerged vehicle operations offer even more. Pedals, shifters, handbrakes, steering wheel, seatbelts, jumper cables, wires, seat springs, and a host of other items offer an excellent chance to snag a hose, tank valve, fin strap, or mask. Simply reaching into a vehicle requires very slow, cautious movements. Additionally, divers must be sure they are carrying multiple cutting tools (at least two pairs of shears and one knife) and that those tools are within reach of either hand in the body’s Golden Triangle (the area between the chin and the lower corners of the rib cage).

Tether line entanglement

Keep a simple rule in mind when moving around vehicles underwater: go over, never around. Moving around a submerged vehicle offers too much potential for entanglement of a tether line in the car’s wheels, undercarriage, bumpers, exhaust pipe or other objects. If the tether line is entangled, tenders and divers cannot send and receive line-pull signals, back-up divers lose direct-line access, and divers lose the ability to make a direct ascent unless they sever the tether line – an extremely undesirable and unsafe situation.

Sharp objects

Since glass is likely to shatter when a vehicle enters the water, you should expect the possibility of sharp, jagged shards. Even shatterproof glass has the potential to cause lacerations. Since many of the cars or trucks that enter the water are not exactly in great condition, be careful of seat springs that can easily puncture a drysuit, glove, or hand. Jagged metal, especially from a damaged vehicle, is the greatest concern. Many divers have sliced open exposure suits and flesh while working on vehicles underwater. Again, move slowly and cautiously. Puncture-resistant linings for gloves are strongly recommended!

Air-filled objects

What do many people have rolling around in their back seats? Empty soda bottles, oil bottles, or cans. What is found in the trunks of most cars? Spare tires. While these objects are normally harmless, underwater they can be dangerous or even deadly. A soda bottle dislodged from under a seat during a search operation can knock out a mask or regulator as it rockets to the surface. A spare tire that pops out when a diver opens a vehicle trunk or rear door can have enough force to break a diver’s neck.

When searching any part of submerged vehicles stay low! Air-filled objects want to go up. If you must pop a trunk, get below the level of the trunk when you open it. Use extreme caution when searching inside as well; even if the spare tire did not come out, it may be unsecured and simply waiting for you to dislodge it. If for some reason you must open a vehicle’s hood, use the same caution. Windshield-washer bottles or other objects can also become dislodged by impact and become underwater missiles. Just remember: "Move slow and stay low!"

Figure 1: Air-filled objects commonly found in cars can become underwater missiles. Air-Filled Objects Found In Cars


If you attempt to rescue victims from a vehicle that is only partially submerged, consider that victims inside may still be alert, because they were able to keep their airways above water. Are you prepared to deal with a panicked, entrapped victim, who may clamp onto you and possibly dislodge your air source? Approach such victims cautiously. Use eye contact to calm them down, and, if possible, have someone from shore use a bullhorn or other amplifier to talk to victims in order to calm them down. However, do not remove your own regulator to talk with them. Removing your regulator can expose you to hazardous materials in the water.

Unstable vehicle/moving water

Never get on the downstream side of a vehicle in a current moving faster than one-quarter knot (25 feet per minute). The moving water will eddy on the downstream side, and the eddying will begin digging a hole in soft bottom just past the car. The hole may eventually become large enough for the car to flip and fall into the hole, creating the potential for a diver to become trapped under it.

Fuel contamination

One of the most dangerous, yet least obvious, hazards of submerged vehicle operations is contamination from petroleum products in the water. Even in a short period, gasoline, oil, and diesel fuel can break down the neoprene and latex of many exposure suits. Upon contact with the skin, they can cause burning and irritation. Fuel in the eyes can cause temporary blindness. High-octane aviation gasoline is particularly nasty, because it eats suits faster and causes more severe burning and blindness. Worse, if divers aspirate oil-contaminated water through wet-breathing regulators or because they take their regulators out of their mouths, they create the possibility of lipoid pneumonia, a life-threatening condition.

Petroleum Contamination Protection Figure 2: Divers should wear vulcanized rubber drysuits and full-face masks to reduce the potential for contamination from the petroleum products found around submerged vehicles.

If you are operating in a recovery mode, do not enter the water without proper personal protective equipment, including at least a trilaminate drysuit or, preferably, a vulcanized-rubber drysuit. Dry gloves, hoods, and full-face masks are also highly recommended. If you are operating in a rescue mode, and do not have drysuits or full-face masks, use extreme caution and be aware of the risks to both your equipment and yourself! While it will not provide 100% protection, using the following guidelines may help reduce risk to divers working on submerged vehicles.

Petroleum products will float to the surface, creating a slick on top of the water. Divers can avoid the slick by going under the water before they get near it, but there is a better option. Certain liquids designed for the purpose can be put on the surface of the water and the divers’ gear that will repel some types of fuel oils. You must check with your local EPA regulations to define whether or not you may use such detergents in your waterways, as they can be harmful to fish and other water life. Dishwashing detergent will also help disperse the slick at least long enough to put a diver in the water. Carry a squirt bottle of quality dishwashing soap (we recommend Joy liquid) and dispense it liberally over the slick. The oil will spread at least long enough to let divers through it. Also, once divers have suited up, you can squirt them down with detergent; as they move through the water, the detergent will wash off them and help disperse petroleum products from them.

One of the most important precautions when working in contaminated water is to keep regulators or full-face masks in place until after divers have been decontaminated! Otherwise, as mentioned, divers face a risk of lipoid pneumonia.

Divers must be thoroughly decontaminated after any submerged vehicle operations. If an exposure suit is already rotting away from petroleum contamination, just cut the suit off of the diver and decontaminate the diver’s entire body. The suit should then be disposed of as hazardous waste. Ensure that any surface personnel are suitably decontaminated as well.


Public safety divers cannot approach a vehicle underwater as though it were sitting in a parking lot. These hazards mentioned are also only a small part of working around vehicles underwater; such operations require not only an awareness of potential hazards, but also thorough, professional training. Without it, untrained divers are simply playing Russian roulette every time they dive around a vehicle in the water.

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Created by Dolphin Diving - copyright 990901