When Lightning Strikes During a Dive

Florida gets more lightning strikes than any other state, and its most recent victim was diver Stephen Wilson, 36, who died in July when a lightning strike hit his tank. Despite a severe thunderstorm warning being in effect, Wilson went diving with three friends in a small boat near Deerfield Beach, 40 miles north of Miami. Wilson had resurfaced 30 feet from the boat when the lightning bolt struck his tank and knocked him unconscious. The other divers struggled to get Wilson back into the boat and radioed for help, but to no avail. He was pronounced dead from electrocution minutes later.

While 75 percent of fatalities by lightning strikes in the U.S. are in open fields or near trees, 12 percent take place in or near the water, in boats and on docks. So potentially, lightning is the biggest weather danger for divers.

Oceans rarely attract lightning because the surface water does not heat up enough to cause the positive charge needed for lightning to occur. Also, water is always the lowest object around, compared to land’s higher elevations and warmer temperatures. But the main problem for divers is that water is a good conductor of electricity, therefore the current of a lightning strike can be carried through water for significant distances. The last jump of a forming lightning bolt is only 100 to 150 feet long, so lightning can strike water more than 150 feet from shore and even if you are considerably below the surface, you can still get electrocuted. However, because the surface of a lake isn’t covered with dead fish after it’s struck suggests the current weakens in short distances.

But what precautions should a diver take while caught in a storm? Are you safer in the water than in the boat? If shore diving, should you stay in the water or go ashore? When I took my basic certification course in the 70’s, we were told to get out of the water in a lightning storm and, better yet, didn’t dive if lightning threatened. Today, however, diving courses are shorter than ever so the question of what to do about lightning is often ignored. PADI’s Open Water manual has no reference to lightning or storms.

Jed Livingston, vice president of training for NAUI, says it’s an obscure risk so there’s no need to cover it in courses. “It might be in our First Aid book but it discusses how to treat an electrical burn. We assume divers already learned what to do a long time ago during their swimming class in school.” Scuba Schools International leaves it up to the instructors’ discretion, says training director Dennis Pulley. “Those who live in areas more affected by lightning are more likely to discuss it with students than those who don’t.”

Lightning is likely to strike the highest thing around so if you’re on the water during a storm, the boat and everyone in it are prime targets. Diving underwater may not be an option because lightning can be even more deadly when its electricity flows through the waves. Underwater caves can be an especially dangerous location. Two cave divers were shocked by lightning while diving in Florida’s Ginnie Springs Cave. They were 900 feet from the entrance when lightning struck - - twice - - but they survived.

If the forecast is for thunderstorms, don’t go out on the water. Or you should return to shore before the storm arrives. If you’re out diving and can see lightning or hear thunder, you’re already at risk for a lightning strike. If the clouds are coming your way, it’s time to head for shore. If you see lightning, the flash-to-bang method can also help determine whether lightning is moving closer (sound travels about one mile every five seconds).

If you’re in a boat during a storm, David Sawatzky, M.D., medical columnist for the Canadian magazine DIVER, says it’s best to huddle in the middle of the boat as far as possible from water, electrical equipment, radios and anything metal. Lower the antenna and anything else sticking up on the boat. If there is a lightning protection system on the boat, don’t touch it.

The ultimate advice is to avoid diving or being in or near water during a storm, and 30 minutes before and after it hits. And don’t sit out on the dock or climb to the top of the boat to enjoy the lightning show.